The linkage between cloud cover, surface pressure and temperature

For the albedo data in this presentation I am indebted to Zoe Phin at. As per usual the temperature data comes from:

Atmospheric albedo is due to particles that reflect visible wave lengths in the spectrum of light emitted by the Sun. This reduces the light that reaches the surface of the planet. Reflection in the atmosphere is due to cloud, and my gut feeling is that the strongest variability will be in the cloud that is in the form of multi branching crystals of ice that create a large surface area in relation to their mass. With a lapse rate of 6.5°C per kilometer, the elevation required to form ice cloud is no more than 3 km over the bulk of the planet and 5 km at the equator. Much ice cloud is seen to be stratified due to localized cooling at a high altitude. With 90% of the atmosphere below 10 km in elevation and ice cloud extending into the stratosphere, its obvious that albedo due to variation in ice cloud density might play a very important part in determining surface temperature. Orthodox climate science tells us that this cloud warms the surface by back radiation. I think differently. The higher the elevation of the cloud the more its density will vary according to the ozone and H2O content of the particular layer involved. And this type of cloud is always layered. It is estimated that about 90% of the albedo of the Earth is due to cloud. Surface features don’t get to play a big role due to the ubiquity of cloud. The question is, which sort of cloud plays what role.

Using satellite instruments that intercept light that is reflected, it has been possible, for more than twenty years, to document atmospheric albedo and chart its variation. So far as I am aware nobody has thought to juxtapose that data with surface temperature. Why? Because of the almost universal assumption that the temperature at the surface is determined by back radiation from the atmosphere, including from cloud, with ice cloud at a high altitude presumed to be partly responsible.

Albedo is measured as the proportion of solar radiation that is reflected towards space with no change in wave length. As we see above, there is a seasonal cycle.

Albedo is at its minimum in August and it peaks in December. The secondary hump in albedo between April and August is explained by the increase in cloud associated with the South and East Asian Monsoon. Eastern China receives about 60% of its rainfall between May and August. The Indian Monsoon is frequently initiated on 1st June. So there should be no doubt that albedo varies with cloud cover.

The data indicates that, between 28% and 31% of solar radiation fails to reach the surface according to the time of the year, due to reflection by atmospheric constituents.

Consider the following argument. As we see above, the temperature of the Earth peaks in July-August. This is coincident with albedo at minimum. The July-August peak in temperature is due to the evaporation of cloud as the land masses of the northern hemisphere heat the atmosphere, driving the dew point down and maintaining more water vapour in its invisible, non reflective, gaseous form. On a regional scale land returns energy to the atmosphere tending to clear the sky during the daylight hours but allowing cloud to return in the late afternoon and evening. Vegetation supplies moisture to maintain cloud so that a fence separating cleared land from native vegetation is frequently observed to be also a dividing line for cloud. So, we know that the supply of moisture and the extent of back radiation from the land surfaces play a big role in determining the presence of cloud. Globally, tropical rain forests in the Congo and the Amazon and across the ‘Maritime Continent’ are the chief sources of atmospheric moisture measured as Total Precipitable Water.

Solar irradiance is 6% weaker in July than in January due to orbital considerations. Now get this! Paradoxically, the temperature of the globe peaks when solar irradiance is weakest. A 5.7% decline in albedo between January and July compensates for the 6% deficit in solar radiation and on top of that, delivers the thumping 2.5°C benefit by comparison with the southern hemisphere. Obviously, this is a feedback driven process that relates to the distribution of land and sea.

This paradox is instructive. Take away the cloud and surface temperature increases. Put the cloud back, and the temperature plummets. Adding the cloud back negatively impacts the Southern Hemisphere in its summer giving rise to cooler temperatures at every latitude than is experienced in the same latitude in the northern hemisphere. The notion that cloud warms the surface via back radiation that is incorporated into the mathematical equations that constitute climate models is erroneous. Cloud normally comes in warm moist air from the equator. Perhaps that is the source of this error.

Over the sea, radiation goes straight into the receipts ledger of Earths energy budget because the sea is transparent. Radiation that falls on land tends to be returned to space with expedition. That is what a comparison of the temperature of the Northern versus the Southern Hemisphere demonstrates.

Its important to realise that any variation in albedo over the land starved Southern Hemisphere that occurs between July and April will be critical to the Earths energy budget.

We need to know what lies behind the variation in albedo including an answer to the ‘where and ‘why’ questions. We can begin with a study of variability by month of year.

The diagrams below are a simple method of assessing the nature of variability in albedo according to the month of the year.

Patently the variation in albedo is a cyclical phenomenon and we have to look for a mechanism to explain it. If we can not explain it and account for it properly we have no business attributing climate change to the works of man. or anything else for that matter.

The interpretation delivered below is based on the reality that the atmosphere of the Earth is in part ionized, especially so in winter and at solar minimum due to the impact of intergalactic cosmic rays. The atmosphere exists in a magnetic field that extends into Space that we call the Magnetosphere. The Earths magnetic field couples to the interplanetary magnetic field to the greatest extent in March and September when the axis of the Earths rotation is at right angles to the plane of it’s orbit.

First see diagram 3. Notice that the pattern in September is a mirror image of that in March. Its hard to make any sense of what’s happening as the Antarctic begins to dominate the evolution of the planetary winds, via its determination of the evolution of surface pressure, between April and August.

Close inspection reveals that the whole of period variation of albedo in October is greater than any other month. In figure 1 we see that the data for October is a mirror image of that in January.

September shifts the August pattern towards what it will become in October. In other words, October magnifies and exaggerates the nature of the variation in albedo that is initiated in September. In November and December, the October pattern is maintained but softened.

November is a very important month for climate. It is in November that the changeover occurs between the Antarctic and the Arctic in the phenomenon known as the final stratospheric warming. The high altitude circulation over the Antarctic changes from descent to ascent with a 180° swing in rotation from ‘west to east’, to ‘east to west’ with the summer rotation a pale version, in terms of the energy involved, of that in winter. With a cessation of descent associated with a fall in polar surface pressure, the temperature of the stratosphere warms to the point where, over Antarctica, it is commonly 20°C warmer at the stratopause than at the equator where the pressure of ionization is most severe. Patently, it is not ionization by solar energy that heats the stratosphere, it the absorption in the infrared by ozone. There is a less exaggerated variation of albedo in November. But, the pattern of variation in November is still like that in September. November albedo is a regular 9-10% increase on that in September. The Earth system is throwing up a cloud umbrella as the Earth gets closer to the sun and solar irradiance gets stronger.

The variation in January is a mirror image of that in December and the January pattern persists into February. The pattern in March is different to that in February, sometimes opposed. However, the disturbance seems to be temporary because the pattern in April reverts to the January-February type.

In September the organizing principle transitions to the form that persists between October and December.

March and September, the months where the Earths atmosphere couples most effectively with the Interplanetary magnetic field are diametrically opposed. It’s as if the atmosphere gets a jerk that temporarily disturbs its habits. The reversion from Arctic to Antarctic control of the global atmospheric circulation occurs in late March, muddying the impact of the coupling of the atmosphere with the interplanetary magnetic field at that time. The ionization of the Arctic atmosphere peaks in January rather than in March. In contrast, the September coupling occurs at a time of strong ionization, and a peak in ozone partial pressure. Ozone is not neutral, electrically speaking. The critical thing to remember is that, via this process the atmosphere is set up to rotate like an electric motor.

There has been a steep recovery in Albedo since 2019 in the months from September through to December. It’s plain that there is an organizing principle that lies behind the variability in albedo and it is very likely to be the response of the atmosphere to the interplanetary magnetic field. Just consider this. The atmosphere rotates in the same direction as the Earth, but faster. Those who are interested in this phenomenon talk about atmospheric angular momentum and a variation in ‘time of day’ that appears to correlate with changes in the planetary winds.

The connection with surface pressure

The flux of surface pressure in high latitudes. directly determines pressure in the mid latitudes in a manner described as the ‘Annular Modes’ phenomenon. Along the equator any increase in surface pressure in the south east of the Pacific Ocean is associated with a fall in temperature as cold water either upwells to the surface along the South American coast or upwells and is is transported westwards along the equator. Where waters are not affected by the mixing of cold with warm or warm with cold, surface temperature varies directly with surface pressure. Along the equator surface temperature rises as atmospheric pressure falls. Under a high pressure cell where the waters are not affected by mixing processes, as the surface pressure rises, so does the temperature of the water, due to a reduction in cloud albedo, exactly the opposite to what occurs at the equator. When this occurs over land, as in the northern hemisphere in summer the impact on surface temperature is immediate and strong. Over the sea, the impact is slight because the ocean absorbs energy to depth.

On a month by month basis surface pressure in the mid latitude high pressure cells of the southern hemisphere depends on pressure in the Aleutian Low and the Icelandic Low. When these cells are are active atmospheric mass accumulates in the high pressure cells of the mid latitudes of the Southern Hemisphere, especially that in the South East Pacific adjacent to Chile. Whereas the Antarctic trough is the background driver of surface pressure across the globe, the vigour of the Aleutian Low has a surprisingly generous impact on the high latitudes of the southern hemisphere between January and March. This directly impacts the ENSO phenomenon via a strengthening of the Trades.

Pressure is normally high in the southern high pressure cells in winter due to the pronounced heating of the northern hemisphere and enhanced polar cyclone activity in the Antarctic trough. This creates a wide zone in the mid latitudes where cloud albedo is naturally low. A strong Aleutian trough delivers strengthening trade winds in the Southern Hemisphere via a boost to the high surface pressure in the Chilean High. The loss of cloud albedo as these high pressure systems expand in surface area, creates a situation where temperature in the mid latitudes increases as it falls across the equator. The enhanced pressure differential between the Chilean High and the Maritime Continent, traditionally monitored by observing an increase in surface pressure in Tahiti against a relatively static pressure in Darwin drives the cooling along the equator. Paradoxically, La Nina is associated with almost invisible additions to the receipts ledger of the Earths energy budget, under the high pressure cells of the Southern Ocean, that is add odds with the evolution of tropical and global surface temperature.

In this way, the Southern Hemisphere is set up to either receive or to reject solar radiation as cloud cover is rapidly growing after the August minimum through to the December maximum. The Southern Hemisphere is mostly ocean and is known to transport energy to the northern Hemisphere, via the diversion of tropical waters northwards due to the arrangement of the land masses.

The diagram below indicates very little change in surface temperature in the southern hemisphere in December when the northern hemisphere is at its coldest and global albedo peaks. The consistent warmth of northern summer in the highest northern latitudes, is due to the invariable surface area of the continents that are responsible for reduction in albedo in mid year. But it is the Southern Hemisphere, picking up energy as the northern hemisphere cools in the last half of the year. that provides the warmth that lengthens the growing season in the northern hemisphere by elongating Summer and Autumn and rendering northern winter warmer than it otherwise would be. The ocean currents that provide this benefit are well known but the source of their variability has long been a matter of speculation.

It’s important to realize that this is a reversible process. Its entirely possible that an increase in albedo affecting the mid latitudes of the Southern Hemisphere will cut off the flow of energy from the southern to the northern hemisphere. Unless there is warming in Southern Hemisphere winter the Northern Hemisphere will see its supply of energy from the south cut off. The gain in temperature seen above, should not be taken for granted. It will not necessarily continue.

Polar regions have lost atmospheric mass over the last seven decades, piling it up most strongly in the mid latitudes. This is assisted by increased convection at the equator. Nothing that is inherent in the Earth system, defined to exclude the influence of the Interplanetary magnetic field, can explain this. The increase in pressure in the mid latitudes affects the differential pressure that drives the South East Trade winds initiated from May through to December and either building or falling away in Arctic winter according to the activity in the Aleutian Trough.

The differential pressure driving the North Westerly winds of the Southern Hemisphere is superior to that driving the Trades and has been increasing apace, over the last seventy years. The differential pressure driving the Westerlies peaks in the middle of winter as surface pressure is enhanced in the mid latitudes against a relatively invariable Circumpolar Antarctic Trough that maintains a resounding planetary low in surface pressure all year round. The increase in surface pressure in the mid latitudes opens an atmospheric window according to the area that exhibits high surface pressure and relatively clear skies. The Trades and the Westerlies come from the same source, the share going to east is unstable a possible subject for another post.

The initiator of variation in ENSO is the high latitude troughs in surface pressure in both hemispheres especially attached to the vigour of the Aleutian trough from October onwards through Southern Hemisphere summer. ENSO is not albedo neutral but the change occurs, not at the equator, but in the mid latitudes.

The movement on the center of convection across the Pacific is a consequence of an increase in the temperature of waters in the East of the Pacific ocean and of no great significance in itself. This is a booster rather than an initiator of the ENSO event. There is little variation in albedo attached to the movement in the centre of convection. The process is started and driven from high latitudes, background condition determined by the Antarctic trough and the month to month swings by the Aleutian Low.

The obvious thing to ask is: How does the variation albedo relate to global temperature?

In the diagrams below the albedo axis on the right, is inverted. As albedo falls away, temperature increases. The relationship is watertight. No other influence needs to be invoked other than ENSO which throws a spanner in the works unrelated to the underlying change in the Earths energy budget.

The relationship between global albedo and surface temperature is less disturbed by ENSO at 20-30S Latitude, the latitudes where the variation in albedo is likely to be directly related to change in surface pressure.

The tropics distort the evolution of global surface in a manner that is unrelated to albedo. Temperature increase in the tropics is important to the global statistic because the circumference of the Earth is greatest in low latitudes. However, tropical variability relates to a mixing phenomenon of cold with warm water that has little to do with albedo and the Earths energy budget. The temperature of the Eastern Pacific that is normally about 8°C degrees cooler than the waters in the West increases in the El Nino phase. But essentially the increase in the East brings temperature to the point where the difference between the East and the West is, for a brief interval, reduced, or eliminated. The result is a leap in global temperature when the high pressure cells in the mid latitudes are contracting and albedo is increasing.

See below

It follows that average global temperature is a not a good guide to the status of the Earths energy budget.

In high latitudes temperature is dependent, not on the ENSO phenomenon or even albedo, but rather the degree of penetration of flows of cold air originating from the Arctic and the Antarctic and that of warm air travelling pole-wards from the mid latitude highs towards the Polar Lows that bring these air masses together. The chief variable here is the surface area occupied by LOW PRESSURE cells (polar cyclones, extratropical cyclones) in high latitudes and the balance of pressure between source and sink with reversals a fact of life. The cooling of high latitudes in the southern hemisphere relates to this phenomenon. Variability in the polar lows occurs on very long time scales. Surface pressure on the margins of Antarctica has been falling for seventy years and the area affected by reduced surface pressure has expanded northwards, especially in winter.

At times when the interplanetary field is less disturbed by solar activity, as we have seen in the most recent solar cycle, large swings in albedo should be expected.


Land and sea surface temperature is very sensitive to albedo on all time scales. Variation in albedo, accounts for the change in surface temperature over the last 20 years, to the exclusion of any other mechanism.

This is a lesson in the the desirability of observation, measuring what is observed and making an effort to understand the mechanism responsible for change. The Arctic Oscillation is well correlated with geomagnetic activity. Shifts in atmospheric mass between the high and mid latitudes change the planetary winds and this is the prime source of change in weather and climate on inter-annual, and longer and decadal time scales. What has been lacking is a close observation of the mechanics of the circulation of the atmosphere in high latitudes in winter and its evolution over time, that is primarily determined in the stratosphere.

Ozone is a greenhouse gas too. There is less ozone than carbon dioxide. But there is enough ozone in the air to impart sufficient kinetic energy to all atmospheric constituents to reverse the lapse rate at the tropopause. The partial pressure of ozone increases in winter when the sun is low in the sky and the short wave radiation that splits the ozone molecule is attenuated. The Antarctic circumpolar trough, the Aleutian Low and the Icelandic Low are made up of one or more polar cyclones. These cyclones can elevate ozone to to the 1hPa pressure level. A polar cyclone that is due to absurdly steep density gradients in the lower stratosphere/upper troposphere, can propagate to the surface because, the surface is simply not very far away. It is in the stratosphere, at Jet stream altitudes, and in the vicinity of polar cyclones, that the climate engine can be found, driving the circulation of the atmosphere. If you are looking to find the engine of climate change at the equator or via ENSO it won’t be there.

What goes up must come down. It (ozone) comes down in the mid latitude high pressure cells that pay scant respect to mans conceptual differentiation between ‘troposphere’ and ‘stratosphere’. The importance of ozone is derived from the fact that it is the only greenhouse gas that is not uniformly distributed and secondly, the virtual absence of ozone in the very cold air descending over the Antarctic, and the Arctic when polar pressure is sufficiently high. The volume of descent of this very cold air is not as important as the maintenance of a steep gradient of temperature and density where the two air masses converge. The notion of a ‘Front’ where these air masses meet, is unphysical. The air rotates in what might be deceptively described as a ‘cold core’ polar cyclone’. In fact the warm core starts at about 500 hPa. There is no ‘troposphere’ at high latitudes. Tropospheric air re-enters high latitudes to establish an ‘ozone hole at Jet stream altitudes in spring. The air that is of tropospheric origin has a high NOx content. Its not there during the winter season.

The descent of ozone into the troposphere has implications for atmospheric albedo. The climate shift of 1978, evident in the evolution of tropical surface temperature in the diagram above, was due to a breakdown of the Antarctic circulation that delivered a steep increase in the temperature of the stratosphere and upper troposphere globally, a subject for another day.

It can be observed that a map of total column ozone is also a map of surface pressure. It is the kinetic energy acquired by ozone aloft that is responsible for low surface pressure. It is difference in near surface pressure that appears to drive the winds. But in a polar cyclone, air density gradients are at their steepest between 500 and 50 hPa, not at the surface. The driver is aloft, not at the surface.

Notions couched in terms of ‘forcings’ of surface temperature based on radiation theory pay no respect to the complexity of the atmosphere and cannot explain the evolution of surface temperature. CO2 has nothing to do with it whatsoever. There is virtue in the study of geography even though its very old fashioned. A study of the geography of the atmosphere is good to combine with a knowledge of the manner in which the temperature and density of the atmosphere has evolved over time, at each pressure level in all latitudes. The temperature of air depends upon where it comes from. That changes systematically over time and with it, albedo.

The parameters that are important to the determination of surface temperature evolve, as does everything in the natural world. The Earth is not an Island unto itself. Unless we identify the correct parameters and study the linkages, the climate system can’t be modelled. When humans pursue ideological objectives its quite common the see them rewrite science to suit their purpose. But, who in their right mind could ignore the importance of cloud as a determinant of surface temperature.

The immediate future

This data above indicates that the change each months data from one year to the next is systematic and progressive, even in the space of 20 years. The ‘clumping’ of several months together all moving in the same direction occurs in the low points of solar cycles. We can see that over the last twenty years the tendency for the variation in albedo between months to be self cancelling, is diminishing. The recent tendency for more grouping in the last half of the year has produced wide swings in surface temperature that are independent of the ENSO phenomenon, affecting the mid and high latitudes rather than the tropics. This week Melbourne experienced its coldest, temperature on record. Some parts of Victoria received half their annual rainfall in two days. Swings to extremes are to be expected when the interplanetary magnetic field is least disturbed during solar minimum and during low magnitude solar cycles that are less disturbing of the interplanetary magnetic field.

The progression of change in March and September is worth examination:

The trend is for albedo to increase in October and for the swings to be wider since 2017. The situation in March is the opposite. The swing in October is more capable of changing the course of global temperatures than that in March. The trend in September-October has, in the past, been maintained through to December. These are important months for both hemispheres.

The big unknown is how the impact of a change in polarity of the Interplanetary Magnetic field, currently underway, impacts the system. Perhaps a person who knows more about electricity and magnetism than I do, can answer that question. Will the next solar cycle be stronger or weaker. If its the former, the Interplanetary magnetic field will be thrown into disarray and its impact on the atmosphere will not have a strong central tendency, to drive albedo either one way or the other.

My gut feeling is that the tendency for albedo to increase will not be turned around for a couple of solar cycles.




Journal of Atmospheric and Solar-Terrestrial Physics

Volumes 90–91, December 2012, Pages 9-14
  • National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 3 G. Bonchev, Sofia, Bulgaria

The strong sensitivity of the Earth’s radiation balance to variations in the lower stratospheric ozone—reported previously—is analysed here by the use of non-linear statistical methods. Our non-linear model of the land air temperature (T)—driven by the measured Arosa total ozone (TOZ)—explains 75% of total variability of Earth’s T variations during the period 1926–2011. We have analysed also the factors which could influence the TOZ variability and found that the strongest impact belongs to the multi-decadal variations of galactic cosmic rays. Constructing a statistical model of the ozone variability, we have been able to predict the tendency in the land air T evolution till the end of the current decade. Results show that Earth is facing a weak cooling of the surface T by 0.05–0.25 K (depending on the ozone model) until the end of the current solar cycle. A new mechanism for O3 influence on climate is proposed.



I disagree with the authors interpretation of the mechanism involved that is described in part as:  increase or decrease of the greenhouse effect, depending on the sign of the humidity changes. 

More simply, the Earths radiation balance is much affected by the degree to which incoming radiation is reflected by cloud cover.

I maintain (suggest is too weak a word) that ozone as an absorber of outgoing radiation by the Earth, radiation continuously, day and night,  impacting the temperature and relative humidity of the highly reflective ice-cloud-zone that is found from a couple of kilometres above the surface of the Earth unto the limits of the ‘weather-sphere’. The weather-sphere, I would describe as the zone that contains sufficient water vapour to promote the appearance and disappearance of  minute, highly reflective, multi-branching  (like the international space station) crystals of ice.

Ice crystals reflect and scatter incoming radiation,

There is no need to invoke carbon dioxide or its increasing presence in the atmosphere, or the notion of a greenhouse effect, to explain surface temperature variations. Insofar as carbon dioxide promotes the growth of vegetation and increases the mass of water in the hydro logic cycle it will promote humidity and the formation of more cloud.

The atmosphere ejects heat by virtue of convection. It lacks any of the properties of a greenhouse. The tragic failure of climate science, in the face of overwhelming evidence to the contrary, is to misunderstand the physics of the atmosphere.

The wilfulness of ignorance and the determination to hang on to old dogma is astounding: this paper appeared in 2012.



The map below has been edited by the author, adding red lines drawn freehand, to outline the darker areas over the oceans where cloud is, on average, less dense. The land tends to be relatively cloud free by comparison with the sea and shows up in tones of blue.In the mid latitudes there is a band of relatively cloud free air over the oceans, a ‘clear sky window’ if you will.

distribution of cloud global

I am indebted to NASA for the photo above and the description of global cloud cover below. The original can be located at

Over to NASA.

Decades of satellite observations and astronaut photographs show that clouds dominate space-based views of Earth. One study based on nearly a decade of satellite data estimated that about 67 percent of Earth’s surface is typically covered by clouds. This is especially the case over the oceans, where other research shows less than 10 percent of the sky is completely clear of clouds at any one time. Over land, 30 percent of skies are completely cloud free.
Earth’s cloudy nature is unmistakable in this global cloud fraction map, based on data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite. While MODIS collects enough data to make a new global map of cloudiness every day, this version of the map shows an average of all of the satellite’s cloud observations between July 2002 and April 2015. Colors range from dark blue (no clouds) to light blue (some clouds) to white (frequent clouds).
There are three broad bands where Earth’s skies are most likely to be cloudy: a narrow strip near the equator and two wider strips in the mid-latitudes. The band near the equator is a function of the large scale circulation patterns—or Hadley cells—present in the tropics. Hadley cells are defined by cool air sinking near the 30 degree latitude line north and south of the equator and warm air rising near the equator where winds from separate Hadley cells converge. As warm, moist air converges at lower altitudes near the equator, it rises and cools and therefore can hold less moisture. This causes water vapor to condense into cloud particles and produces a dependable band of thunderstorms in an area known as the Inter Tropical Convergence Zone (ITCZ).
Clouds also tend to form in abundance in the middle latitudes 60 degrees north and south of the equator. This is where the edges of polar and mid-latitude (or Ferrel) circulation cells collide and push air upward, fueling the formation of the large-scale frontal systems that dominate weather patterns in the mid-latitudes. While clouds tend to form where air rises as part of atmospheric circulation patterns, descending air inhibits cloud formation. Since air descends between about 15 and 30 degrees north and south of the equator, clouds are rare and deserts are common at this latitude.Cloud Africa

Ocean currents govern the second pattern visible in the cloudiness map: the tendency for clouds to form off the west coasts of continents. This pattern is particularly clear off of South America, Africa, and North America. It occurs because the surface water of oceans gets pushed west away from the western edge of continents because of the direction Earth spins on its axis.
In a process called upwelling, cooler water from deep in the ocean rises to replace the surface water. Upwelling creates a layer of cool water at the surface, which chills the air immediately above the water. As this moist, marine air cools, water vapor condenses into water droplets, and low clouds form. These lumpy, sheet-like clouds are called marine stratocumulus, the most common cloud type in the world by area. Stratocumulus clouds typically cover about one fifth of Earth’s surface.
In some of the less cloudy parts of the world, the influence of other physical processes are visible. For instance, the shape of the landscape can influence where clouds form. Mountain ranges force air currents upward, so rains tend to form on the windward (wind-facing) slopes of the mountain ranges. By the time the air has moved over the top of a range, there is little moisture left. This produces deserts on the lee side of mountains. Examples of deserts caused by rain shadows that are visible in the map above are the Tibetan Plateau (north of the Himalayan Mountains) and Death Valley (east of the Sierra Nevada Range in California). A rain shadow caused by the Andes Mountains contributes to the dryness of the coastal Atacama Desert in South America as well, but several other factors relating to ocean currents and circulation patterns are important.
Note because the map is simply an average of all of the available cloud observations from Aqua, it does not illustrate daily or seasonal variations in the distribution of clouds. Nor does the map offer insight into the altitude of clouds or the presence or absence of multiple layers of clouds (though such datasets are available from MODIS and other NASA sensors). Instead it simply offers a top-down view that shows where MODIS sees clouds versus clear sky.
Since the reflectivity of the underlying surface can affect how sensitive the MODIS is to clouds, slightly different techniques are used to detect clouds over the ocean, coasts, deserts, and vegetated land surfaces. This can affect cloud detection accuracy in different environments. For instance, the MODIS is better at detecting clouds over the dark surfaces of oceans and forests, than the bright surfaces of ice. Likewise thin cirrus clouds are more difficult for the sensor to detect than optically thick cumulus clouds.


Cloud levelsAbout half of the atmosphere is below 5 km in elevation and half above. Cloud is present in both the upper and the lower half of the atmospheric column.  In near equatorial latitudes very high cloud extends into the stratosphere. The jet streams at 8-15 km in elevation were first identified by tracking the movement of cirrus clouds.


Landscape from space

The photo above was taken from the International space station at an altitude of 431 kilometres above the surface of the Earth. A red circle is marked in the sea off Christchurch, New Zealand.

Gravity holds the Earth’s atmosphere in a close embrace.  Really close. As seen in the photo the atmosphere refracts blue light like a prism on the margins of the globe. The red line at the margin, in its thickness, represents a depth of about 27 km. Some 98% of the atmosphere lies within 27 km of the surface of the planet.

Project Loon, a venture by Google, employs balloons that travel at an elevation of 20 km finding sufficient variation in the winds to enable these balloons to circumnavigate the globe in 10 days and land at preordained locations.

In 1920 Gordon Dobson registered his interest in the winds of the stratosphere using theodolites to track sounding balloons. Strong winds in the stratosphere led Dobson to the measurement of ozone as the source of density variations that could explain these winds.

The stratosphere is a vigorous medium. The tongue of mesospheric air inside the polar vortex penetrates to the 250 hPa pressure level at 8 km of elevation and tracers of mesospheric air from both the mesosphere and the near surface atmosphere can be observed mixed with ozone throughout the stratosphere. NOx is a potent source of ozone depletion  changing surface climate because of its effect on ozone and surface pressure.

In 1956 when a Dobson spectrometer was utilized to measure total column ozone for the first time at the British Antarctic base at Halley Bay, the Antarctic  ‘ozone hole’ was discovered, amazing Dobson who was familiar with the pattern of ozone variation in the Arctic and therefore completely outside his field of experience. This ‘hole’ was later seized upon by environmentalists  as an instance of man’s capacity to abuse the planet.In truth, the 1956 observation indicates that the ozone hole existed prior to the widespread use of refrigerants and is a product of the atmospheric circulation in high latitudes. The ozone hole narrative, a pillar of today’s climate science’ stands in the way of a true appreciation of atmospheric processes.


The atmosphere is heated by contact with warm surfaces, secondly at cloud level by the release of the latent heat of condensation (notably tropical cyclones) and thirdly in the  as ozone absorbs radiation from the Earth itself. Low pressure systems at latitudes between 30° and 70° of latitude have their origin in ozone heating. These low pressure cells set up a rising circulation that engages the totality of the atmospheric column. In mid to high latitudes ozone is the primary driver of lapse rates. In high latitudes ozone is ubiquitous throughout the atmospheric column. Low pressure systems (cold core polar cyclones) form over the oceans. In the northern hemisphere winter the Pacific sector in overwhelmingly dominant. Once initiated in the stratosphere, a low pressure system lifts ozone into the ascending circulation accounting for the relatively static  location for elevated total column ozone and markedly lower surface pressure over the north Pacific in late autumn/ winter. In the southern hemisphere polar cyclones surround the Antarctic continent with a tendency to be most intense south of New Zealand.

A high pressure system in the mid latitudes can span 3,000 kilometres in its horizontal extent and manifestly involves the circulation of the air in both the troposphere and the stratosphere. As surface pressure increases so does geopotential height, indicating ozone heating. In chapter 3 we noted that the surface warms as geopotential height increases as a simple result of the expansion of the ‘clear sky window’.

At the equator convective clouds push wet air upwards to 15 km in elevation and moist air rich in tropospheric NOx invades the stratosphere, the prime reason for the relatively low levels of total column ozone in low latitudes.It is for this reason that high pressure cells are much denser aloft than low pressure cells, compensating for the warmth and lack of density near the surface to the point that surface atmospheric pressure is enhanced.

The novelty of this view of the atmosphere resides in the recognition of ozone as the source of surface pressure variation. It is in the mid to high latitudes of the winter hemisphere that surface pressure varies most aggressively. Secondly the novelty resides in the view of the stratosphere as a vigorous deterministic medium. Thirdly, it is novel in the notion that the entire atmospheric column moves ‘wholus bolus’ with scant regard to conceptual notions relating to a vigorous ‘troposphere’ and a static, quiescent stratosphere.

As Gordon Dobson observed back in the thirties , total column ozone maps surface pressure, the ozone content of the upper air determining the character of the winds at the surface. In fact, this view of the atmosphere is not so new. It was prevalent in the 1950’s when RM Goody, a colleague of Dobsons at Cambridge wrote:’The idea is gaining ground that, from the dynamical standpoint, the stratosphere and the troposphere should be treated as a single entity’. RM Goody, The Physics of the Stratosphere 1954. p. 125.

Our imaginations baulk at the idea that the atmosphere is thin and vertically interactive. The mental constructs that we have been taught, involving a supposedly quiescent stratosphere, lead us astray, especially when it comes to appreciating atmospheric dynamics in high latitudes.   High latitudes are so cold that few of us venture there. A very few hardy souls actually reside there. One thinks of the monkeys who take advantage of hydrothermal energy in northern Japan, the hardy Eskimos of North America and the wildlife that visits Antarctica for the ‘season’.

Palpably, change in what we refer to as ‘the stratosphere’ is the source of variations in surface pressure on daily, weekly, decadal and centennial  time scales. The stratosphere has a geography that is as fascinating as that at the surface of the planet, in fact, given its importance in determining daily weather it should be more so. The search for the origins of natural climate variation takes us inevitably to the stratosphere. In order to appreciate the power in the processes involved we need to maintain a sense of scale. This helps us to understand the coming and going of cloud, the most important determinant of surface temperature.


In the main cloud is made up of highly reflective crystals of ice because within a couple of kilometres of the surface, in temperature latitudes, temperature is at freezing point. Less cloud forms over land. The mid latitude high pressure cells are relatively cloud free. These clear sky windows expand and contract on a seasonal basis being more expansive in the winter hemisphere driven by heating in the summer hemisphere and a seasonal movement in atmospheric mass from the high latitudes of the winter hemisphere. It is the accumulation of ozone in the winter hemisphere that drives inter-annual climate variations. It is the ozone narrative of the environmental movement that stands in the way of an appreciation of the source of natural climate variation.


The phenomenon of mass transfer associated with ozone heating in high latitudes in winter has long been described as the Arctic or the Antarctic Oscillation, or on a regional scale as the North Atlantic Oscillation. Only recently has it come to be called the ‘Annular (ring like) Modes of inter-annual and inter-decadal climate variation’ that affects both hemispheres primarily in winter.

There is a very long period of variation in the Antarctic Oscillation that is undocumented. It is inter-centennial in its time scale and we don’t have the data to represent it. As of 2015 reliable data for the atmosphere goes back just 70 years. Of that period the first thirty one years has been documented by a process of interpolation based on sketchy data from the pre-satellite age and this especially applies to the southern hemisphere.

We have excellent well standardised data from 1979 from a few well maintained and closely scrutinised instruments that travel around the globe on a twice daily schedule, an immense improvement on the past where many instruments, poorly standardised, poorly located, subject to re-siting and the vagaries of interpretation by multitudes of observers, but during working hours only, who could nevertheless cover just a fraction of the whole with spot rather than continuous observations. Observations were recorded on fragile pieces of paper. Data from the pre satellite age is ……well, despite all the effort, very hard to locate, full of gaps, in the case of temperature much affected by the choice of housing for the instrument and change in the local built and natural environment, therefore of questionable utility and much subject to ‘reinterpretation’. But, there is one parameter in the climate record, atmospheric pressure, that is entirely unaffected by the choice of location for the instrument. The instrument we call a ‘barometer’ that works as well on a rolling ship as on land, in the sun or in the shade. There is therefore no reason for re-interpretation  of the surface pressure record.

Here is the kicker: The surface pressure record indicates that it is in high southern latitudes that surface pressure varies most widely. It also indicates that there has been a loss of atmospheric pressure over Antarctica of about 15 hPa over the last 70 years.

Those who are employed to predict the weather diligently map surface pressure variations and they see the origin of surface pressure variation here:

Their focus is on the stratosphere.


Observe the dense cloud cover over the Congo in the second photo above,and to a lesser extent over East Africa by contrast with cloud cover over the Sahara and the Kalahari Desert in Southern Africa and the very cold waters coursing northwards from Cape Town.

It takes particular circumstances to produce cloud over land in summer . What is required is a cover of actively transpiring vegetation that launches water vapour into the atmosphere. Nowhere is this more obvious than the zones that support tropical rain forest. As a general rule, if we desire cooler surface temperatures and more precipitation we should plant trees and avoid clearing high density vegetation unless it is to be replaced by a higher density of vegetation. It is commonly observed in the more arid portions of Australia that cloud forms over native vegetation rather than land cleared for pasture or grain growing.

From a plants point of view carbon dioxide is a scarce resource that is available at near starvation levels. When more carbon dioxide is available plants that are at the dry end of the spectrum in terms of available water respond magnificently. Australian CSIRO scientist Randall Donohue published the image below that documents the re-vegetation response to carbon dioxide . Apparently, the drier the environment the better the foliage gain from increases in CO2. This gain documented in the map has accrued between 1982 and 2010. Source:


Urbanization has contributed to the warming of the planet as societies have cleared natural vegetation, industrialized, laid down roads to facilitate the  movement of people and goods on a massive scale, provided lighting at night, expanded the suburbs on the margins of cities and built glass covered multi story buildings that trap heat and require air conditioning. Man has harnessed the power of fossil fuels, falling water, the sun and the wind to drive engines to perform work and to cool and warm the structures he creates. All this results in localized heating but the area involved is tiny. Look for the night lights as you travel by air and observe their sparsity. Trust to enhanced convection to deal with the temperature increase. Remember that much of the Earth is undesirably cool from the point of view of plant productivity.

All life depends upon the productivity of plants and much of the earth is arid. It is in these areas that enhanced availability of carbon dioxide gives the greatest response. Remember that there is nothing like native vegetation for producing clouds and cooling the surface. With the enhancement of carbon dioxide in the atmosphere the earth is entering a golden age of enhanced plant productivity.

Along with enhanced leaf area in dry areas we get greater evaporation, greater cloud cover and enhanced rainfall.Irrigation of dry areas enhances this process actively changing the climate for the better.


The two maps  below reflect the distribution of cloud and surface atmospheric pressure. Large areas over the oceans experience high surface pressure, sparse cloud cover, low precipitation and relatively high evaporation.  Except for a band of high precipitation extending south easterly from New Guinea almost the entire zone between the equator and 30° south is ‘clear sky window’. The sea traps energy by virtue of its transparency to as much as 300 metres in depth.  It yields that energy slowly, transferring it to colder regions. Operationally, if one were to increase the areas that are coloured brown you increase the energy cycling within the ocean and this raises the surface temperature of the globe. The flux in the cloud free areas involved is driven by the annular modes phenomenon, a response to ozone in the stratosphere.

Observe the symmetry in the two maps below. The distribution of evaporation less precipitation maps surface pressure and the distribution of cloud.

Evaporation minus precipitationSource:

distribution of cloud global


Consider the annual average of global air temperature as against top of atmosphere global outgoing radiation as documented on the left and right axis of the figure immediately below. The placement of the curves in the vertical dimension is arbitrary.I bring them into close association only to assess variation in their evolution according to the time of the year.

A system that is neither heating or cooling needs to be in balance across the year. From September through to January outgoing long wave radiation lags the temperature curve indicating energy entering the system in excess of that leaving. This seasonal increase in energy acquisition relates to the annular mode phenomenon. It is at this time of the year that the southern and the northern annular modes most drive change in the distribution of atmospheric mass opening up the ‘clear sky window’. In effect the ocean absorbs energy without immediately re-transmitting it.

OLR and Air T

In a system where surface temperature is static then outgoing long wave measured at the top of the atmosphere should also be static. Below is the data for both air temperature in the 0-30° latitude band (where the clear sky window is most extensive) and whole of Earth outgoing long wave radiation. Since 1998 both are essentially static despite the steep increase prior to that date. In the short term air temperature in the near tropical ocean is a function of the changing volumes of cold water introduced into the tropics due to flux in the planetary winds but in the long term these two series must vary together.

OLR and progress of T

The stabilization of  long wave radiation after 1998 at about 230 watts per square metre indicates a system that is no longer gaining energy. This, despite the vagaries of change in surface temperature, is the plain reality.

In the relatively cloud free zone between the equator and 30° of latitude  we would expect temperature to increase as surface pressure increases due to an expansion of the ‘clear sky window’. The diagram below indicates a relationship but it is plainly not direct, at least in the short term and we see that the increase in temperature frequently precedes the increase in surface pressure.Why is this so? There are several reasons:

  1. Ocean currents driven by the planetary winds  bring cold water from higher latitudes into the tropics displacing warmer water, the primary mode of short term variation in the temperature of the waters in the tropics.This acts to cool the tropics as surface pressure increases in mid latitudes opening the clear sky window that warms the extra tropical waters.
  2. A  strong warming dynamic in the South Eastern Pacific about the continent of South America precedes the temperature increase in the tropics by as much as a year. The flux in surface pressure across the Pacific is much stronger than across other oceans or indeed the global tropics taken as a whole.
  3. The Arctic Oscillation Index is currently in decline indicating an increase in surface pressure in the Arctic, a loss of surface pressure in the mid latitudes and a falling away of the strength of the winds that drive the circulation of the waters in the northern hemisphere. So, since 1998, El Nino bears the stamp of Arctic processes in the way that it manifests.

Temperature and pressure


  1. Earth is a very watery, very cloudy planet much subject to temperature swings according to the extent and density of cloud cover.
  2. Over land, 30 percent of skies are completely cloud free but the land is incapable of transferring energy to depth or retaining it and transfers that energy to the atmosphere, mostly within the 24 hour cycle, in the process reducing cloud cover in the middle of the day and allowing it to increase in the late afternoon. The annual cycle in global temperature involves a maximum  in northern summer as the enormous land masses of the northern hemisphere heat the atmosphere and cloud falls away. Solar radiation is 6% less intense in northern summer due to orbital considerations. However a falling away of cloud cover at this time of the year allows more energy to reach the surface producing a temperature maximum for the globe as a whole in mid year.
  3. The oceans are transparent to solar radiation and consequently store energy. Over the oceans, less than 10 percent of the sky is completely clear of clouds at any one time. This limits the uptake of energy by the oceans delaying and transferring the surface temperature response to a reduction in cloud cover. In clear waters light penetrates to a depth of 300 metres.
  4. Two thirds of the global oceans are in the southern hemisphere.
  5. Globally, cloud cover is greatest in southern summer when the Earth is closest to the sun and solar radiation is 6% stronger due to orbital considerations. This is when the globe as a whole is coolest and most susceptible to warming via loss of cloud cover. The evidence is that between September and January, the Earth emits less energy than it receives. At this time polar processes drive change in atmospheric ozone levels from year to year and across the decades.
  6. The expansion and contraction of the Hadley cell in the southern hemisphere affects the distribution and extent of cloud across the southern hemisphere. On an inter-decadal scale an expansion of the Hadley cell as surface pressure rises in the mid latitudes exposes more of the southern oceans to solar radiation. This is palpably the most important dynamic driving global surface temperature in the long term. Neither this nor the impact of ozone in driving  shifts in atmospheric mass that lies behind the expansion of the Hadley cell are recognized in the works of the UNIPCC.
  7. The Southern and the Northern Annular Modes govern the extent of the relatively cloud free high pressure cells that form over the ocean The NAM is influential in determining the swings in surface temperature between  30° south latitude and the northern pole with regular repeating variations that reach a maximum in January and February. The SAM cycles on an inter-centennial time scale providing the long swings upon which the NAM creates the surface chop.It produces the largest temperature swings that are seen in June and July south of 30° south. Although apparently lacking potency by comparison with the NAM on a centennial scale the SAM is much more variable than the NAM and drives the whole.
  8. The origin and cause of the NAM and the SAM is unknown to climate science because the role of ozone in giving rise to polar cyclones that determine the flux in surface pressure in high southern latitudes is as yet unrecognised. The most important source of convection, the jet streams and the flux in the weather on all time scales is still a mystery to climate science even though the importance of the stratosphere in determining the flux in surface pressure was realised a hundred years ago. The source of the natural variability that vacillates on centennial time scales is not a question that exercises the minds of climate scientists. Climate science of the IPCC variety appears to be blissfully unaware of the marked loss of mass in high southern latitudes over the period of record.
  9. In Southern summer the concentration of ozone in the global stratosphere is controlled by Arctic stratospheric processes. This is expressed as a dynamic fluctuation in surface temperature in the 0-30°south latitude band, and across the entire northern hemisphere, in the months of January and February. This is the signature written in the temperature record that identifies the source of surface temperature change.
  10. Surface temperature anomalies are associated with anomalous increases in geopotential height that manifest from the surface through to the stratosphere. This surface temperature increase is related to cloud cover variation due to ozone heating. We know this is the case because the temperature of the upper air varies more strongly than the air at the surface. It is not possible for change at the surface to produce an amplified change at elevation. Dissipation rather than gain is the rule.
  11. As a surface dweller humans are well aware that temperature varies according to the origin of the air that meets us when we step outdoors in the morning. Change in the planetary winds changes the origin of surface winds and is conjunction with change in surface pressure, geopotential height and upper atmosphere ozone. The chain of causation is top down. Climate science as presently  promulgated is unaware of this dynamic. It is in a sad state of constipation due to an ideological insistence that change must be bottom up in origin. Climate science is unaware of the basic dynamic governing the planetary winds and surface temperature.
  12. Recognition of ozone as the driver of the annular modes via the marked increase in ozone partial pressure outside the margins of the tongue of mesospheric air that descends from the stratosphere would interfere with the favoured ozone hole narrative of environmentalists. The Montreal Protocol for the phasing out of certain chemicals used as propellants and refrigerants,  a high water mark for the environmental movement  would then be seen as resulting from a mistake in the interpretation of atmospheric processes. There is too much at stake for the environmental movement to revise its opinion on this matter.
  13. Given the active circulation in the global oceans the temperature of tropical waters is probably a reasonable indicator of the amount of energy stored in the system, at least on decadal scales that average for the flux in the planetary winds and the resulting ENSO phenomenon. The rate of inflow of cold waters into the tropics via the currents that flow equator-wards along the western margins of the continents is highly variable. It is driven by the planetary winds that vary in velocity with changes in surface pressure. It is commonly observed that tropical waters cool as the trade winds strengthen. Increased velocity in the trade winds and the westerlies is due to the transfer or atmospheric mass from high to mid latitudes as ozone levels increase at the pole driving enhanced vorticity in cyclones of ascending air and the jet stream aloft. This is in turn associated with increased geopotential heights in the mid latitudes reduced cloud cover and surface warming. So, we have a conjunction of mid latitude warming due to reduced cloud cover and cooling in the tropics as increased wind velocity drives more cold water into the tropical circulation displacing warm waters into higher latitudes to raise surface temperature in those higher latitudes as it falls in equatorial latitudes. The action that really matters, in terms of energy acquisition, happens outside the narrow latitudes where ENSO is measured and in the southern hemisphere in particular.For most observers this is mind boggling.Those who look for the origin of the El Nino phenomenon are looking in the wrong place if they confine their attention to the narrow latitude bands where surface temperature varies most strongly.
  14. By virtue of the area involved, the tropics as a whole makes a large but somewhat misleading contribution to the global temperature statistic. The flux in temperature in the tropics is large in amplitude but it is driven according to a longer time schedule, years rather than months in accord with change in the planetary winds. The flux in temperature in the mid to high latitudes is vigorous, particularly so in the northern hemisphere and peaks with monotonous regularity in particular months of the year under the influence of polar atmospheric processes.
  15. Change in sea surface temperature on inter-decadal time scales is signalled in the months of January and February and July through to October under the influence of the Arctic and the Antarctic respectively. The change in surface temperature in other months is muted by comparison and in some instances opposite in sign to that in the months that show peak variation. There is no apparent groundswell of temperature increase across all months in accord with the increase in the atmospheres burden of well mixed long wave absorbers that would indicate a greenhouse effect at work.
  16. Taken together, these observations support the contention that cloud cover is the prime source of variation in the amount of solar energy stored in the earth system.
  17. The atmospheric column over Antarctica is the source of climate variation globally. Change in geopotential height over Antarctica precedes change elsewhere frequently imposing mirror image responses in the Arctic.
  18. Extremes in weather in the tropics, such as tropical cyclones and cyclones of polar origin are driven by entirely different modes of causation, the former by warm seas, moist air and precipitation the latter by change in the ozone content of the air aloft. We do not have to have recourse the grab bag called ‘climate change’ that implies anthropogenic modes of causation to explain extremes in climate and weather. We should be more discerning, more observational and more logical, in our thought processes. Currently those who pretend to have all the answers are behaving like primitives.



Immediately beneath this sentence is the interface of the ESRL Website at:

ESRL interface

The interrogation that is entered in the form relates to sea surface temperature at 20-40° south latitude around the entire globe (0-360° longitude) taking into account every month of the year adjusting for the reducing circumference of the Earth as latitude increases, presented as a plot. That plot is below.Graph SST

I live at 34° south latitude and at this latitude there is mostly ocean rather than land. Home is on the south-west coast of Australia where the winds are mostly onshore. So, air temperature tends to follow sea surface temperature. I am a farmer and all farmers take a strong interest in climate. I grow grape vines and make wine. The wine expresses the variations in the climate from year to year. To make good wine, the best wine possible, I need to know what is going on. I am told that the climate is getting hotter and I may need to plant later ripening varieties to avoid damaging heat during the ripening period.

All that we can say about this data is that temperature has increased in both winter and summer. But spring and autumn is important to me. The vine leafs out in spring and the fruit matures in autumn. I need to dig deeper.

The data can be acquired in the form of an array of monthly averages as seen below. Its a long sheet of data and I show you just the top and the bottom of the sheet.

SST data top

SST bottom

I want to show you how to work with the raw data to get a much better idea of what is going on in your habitat. Since climate varies primarily according to latitude I define my own habitat, in the first instance, as a band of latitude. If you prefer, you can focus on just part of a latitude band and perhaps air temperature rather than sea surface temperature if you happen to live far from the sea. In this exercise I am going to focus on the entire band of latitude because I am interested in the way climate changes globally.

Copy the data directly from the ERSL website and paste using a simple ‘notepad’ format. Save this as a text file. This is what the notepad sheet looks like.

SST notepad

Next step is to import that data into a spreadsheet via the import wizard available in excel.Text import wizard

Below, the spreadsheet is represented in part with some calculations in red text and a graph of the data in red.

Annual average SST 20-40° south

I have added each months data from January through to December and divided by 12 to yield the annual average. Then I have plotted the column in red. What can we see:

  1. There has been an increase of 0.4°C in temperature in this latitude band over the last 67 years. However, this is within the range of the most extreme inter-annual variability (more than 0.5°C) so it is possible that the factor causing the temperature to swing between the years is also responsible for the whole of period change.
  2. Extreme inter-annual variability prior to 1978 and much less after 1978.

The expansion of the Hadley cell and the consequent southward migration of the mid latitude high pressure cells after 1978 is a feature than many observers have remarked upon. High pressure cells dominate this band of latitude. Summers are dry. In winter fronts attached to low pressure cells that impinge at this time of the year bring rain. The lack of variability post 1978 suggests a reduced incidence of cold winds from the south.  High pressure cells are relatively cloud free. If there is less cloud it can’t come and go. With an expansion of the Hadley cell one would see fewer fronts associated with low pressure cells so the fluctuations in surface temperature would tend to diminish along with the rainfall. Indeed rainfall has declined by 15-25% depending on location.


By adding all Januaries and dividing by 68 (68 Januaries) the average temperature for the month of January over the period 1948-2014 is obtained. It is 22.32°C. Paste the formula across the page. Graph the result as the average monthly temperature.

Average daily temperature is sub optimal for photosynthesis (25°C is optimal) in all months but daytime temperature in the height of summer is almost warm enough to be optimal.  Growth of plants is very slow in the winter months. An extension of the warmth of February into the months of March through to June would increase plant productivity but unfortunately, without irrigation this can not happen. However, grape vines are hardy plants and this is their natural habitat and the best wines come from non irrigated vines. Less rain means less fungus and less spraying so it’s all good.

I want to see how sea surface temperature has evolved over the decades. The process is shown below. First copy and paste the average monthly temperature for the entire period to the head of the spreadsheet immediately adjacent and to the right of the raw data. Follow in the next row with a label for each month. In the next row calculate the difference between the raw data for a particular month and the average for that particular month for the entire period. For instance  raw data for January 1948 is a temperature of 21.957°C and the average for the entire period for the month of January is 22.32128, the difference being 0.36428°C. This statistic is the ‘anomaly’ with respect to the average for the entire period.

Anomaly 1948-56

I plot the anomaly for the period 1948-56 together with the average for that period of 9 years and you see it above. Its plain that this decade was cooler on average especially in April and May. I work through the decades.

When I get to the decade 1997-2006 I see this:

SST Anom 20-40S 1997-2006

The months that were very cool in the first decade are very warm in 1987-96. The months that were slightly anomalously cool in 1948-56 are still slightly anomalously cool.  This is interesting. If there is a greenhouse effect due to increasing carbon dioxide in the atmosphere why is there so small a temperature increase in spring and so large an increase in autumn over this sixty eight year period?

So, I plot the average for each decade and here it is:

Decadal change

It turns out that in the intervening decades, and in particular from 1957 until 1976 the first half of the year has been very much cooler than both the first and the last decade. There is very little change between the first and last decade. Much wider swings have occurred in the past. The decade 1977-86 was much warmer in spring and early summer than it is in the last decade. The decade 1997-2006 that saw some of the warmest years globally in terms of annual averages is the coolest within this particular band of latitude.

Obviously, there is a factor involved that can produce warming AND COOLING and climate change is not a one way train.

Obviously, annual averages are not the appropriate metric if we want to discover the sources of natural variation in climate. We need to focus on monthly data.

What is to come in this blog/book?

If you are genuinely interested in the question of whether man has an influence on the climate then read on.  If you want to know what the sources of natural climate variation are then read on. But if you would rather engage in a ‘willing suspension of disbelief’ as most of us do when we go to the movies or to church on Sunday, and you are ideologically committed to the notion that man is responsible for climate change and are not willing to consider any other possibility then this is not the place for you. In short order you will be confronted by things that will bother you and you will become uncomfortable.

If you can look at data and ask yourself ‘why is it so’ please come along for the ride.