12 VARIATION IN ENERGY INPUT DUE TO CLOUD COVER

Ninety nine percent of the atmosphere lies within the ambit of a vigorous day’s walk, just 30 kilometres!

The atmosphere efficiently conveys heat to space via convection (transport) and radiation.  This is apparent in the 24 hour cycle of temperature as a point on the Earth’s surface alternately faces the sun and enters the night zone and the more so in inland locations where the daily range of temperature is accordingly much greater.We call this increase in the daily range of temperature the ‘continental’ effect.

In the northern hemisphere where there is a relative abundance of land the seasonal extremes are wider we have another example of the ‘continental effect’. The strong maximum in outgoing radiation in summer should promote summer warming if the atmosphere were subject to a ‘greenhouse effect’. But, consult the graph below and see that in the mid latitudes of the northern hemisphere we find that the temperature has increased mainly in spring and autumn. In high latitudes the increase in temperature has been in winter when outgoing radiation plunges to a  minimum.

Change in T in NH according to month of the year

Under an imaginary greenhouse regime the atmosphere becomes an impediment to heat transfer and we should see an increase in temperature in all seasons and in all locations just as the ocean limits the variation in temperature of proximate locations. But in fact we observe that the temperature increase that has occurred is variable according to the month of the year. This temperature increase does not tally with the mechanism that is proposed by the United Nations International Panel on Climate Change that was set up to examines man’s influence on the climate of the globe.

In cold conditions humans make sure that the air close to their skin is contained and unable to move. But, the Earth’s atmosphere is not confined in this way. Consequently it acts as a river for energy transfer from the surface to space. As a river it is perhaps the most vigorous on the planet. The ‘supposed greenhouse effect’ is no impediment to this process. Common sense dictates that a static atmosphere is required if the rate of loss of energy is to be curtailed and back radiation is to return energy to the surface via a so-called greenhouse effect. The atmosphere is anything but static. We insulate to stop the air moving. The atmosphere is air.

Plainly we must look to other modes of causation to explain the temperature increase that has been observed.

NATURAL VARIATION IN ENERGY INPUT AS MEDIATED BY CLOUDS

The following observations demonstrate the primacy of cloud that acts to reflect solar radiation, so determining surface temperature:

  1.   For the globe as a whole the sea is always warmer than the land and the global average for both the land and the sea is greatest in July.Global sea and air
  2.  A maximum in June/July is an anachronism. Earth is farthest from the Sun on July 4. The quotient of energy available from the sun (above cloud level) is 6% less in July than in January.

Why is the Earth warmest when it is most distant from the sun?

In northern summer the sun heats the abundant land masses and the land being opaque the surface quickly warms and with it the atmosphere.  The supply of water vapour to the atmosphere lags behind the increase in the water holding capacity of the air. There is less ocean in the northern hemisphere. In any case water is transparent and it stores energy to depth releasing it slowly. The upshot is that the heating of the atmosphere by the land rich northern hemisphere directly and dramatically reduces cloud cover.  The July maximum in global temperature is due to an increase in the diminished total of solar energy that is available in July. The amount made available at the surface is so much greater in mid year as to result in a temperature peak in mid year.

In northern autumn gathering cloud reflects more solar radiation and the globe therefore cools as its orbit takes it closer to the sun. That’s a pity because as I explained in the last post the globe as a whole is cooler than is desirable from a plant productivity point of view and all life ultimately depends on plants.

MEASURES OF CLOUD INTENSITY

From:http://www.iac.es/adjuntos/cups/CUps2015-1.pdf we have direct measurements for Izana observatory in the Canary Islands of  the number of days where cloudiness (red and yellow) is recorded and conversely the number of days where the sky is sufficiently devoid of clouds to achieve a clear sky rating (green).  The attenuation of cloud cover in northern summer is evident.
Cloud cover Teide Observatory, Spain

EFFECT OF CLOUD ON INCIDENT SOLAR RADIATION

From http://www.ccfg.org.uk/conferences/downloads/P_Burgess.pdf we have direct measurements of solar radiation at the surface.

Radiation as a function of time of year and cloud cover in Bedordshire

At this site in the UK cloud is responsible for the attenuation of solar radiation by a minimum of 26%  and a maximum of 90%.

EFFECT OF CLOUD ON SURFACE TEMPERATURE

Surface temperature is directly modulated by cloud cover as demonstrated in the following satellite photograph.Temp varies with cloud cover

image:http://www.weathercast.co.uk/weather-news/news/ch/a9b4bc85105a36c329ffc8cee57292b2/article/why_is_forecasting_cloud_cover_so_difficult.html

DISTRIBUTION OF CLOUD DRIVES SURFACE TEMPERATURE AND IS ALLIED TO CHANGE IN SURFACE PRESSURE AND GEOPOTENTIAL HEIGHT

It should be abundantly clear that it is the mediation of energy input by clouds that is the most influential determinant of surface temperature. Zones that experience high surface pressure are relatively cloud free. The essence of change in the ‘annular modes’ lies in a shift of mass from high latitudes due to ozone heating that drives down surface pressure. High southern latitudes have lost atmospheric mass for seventy years on the run. Lost mass has been distributed across the globe adding to surface pressure in those parts of the globe where increased surface pressure  is allied with relatively cloud free skies. In chapter 3 we observed that the globe warms when geopotential height increases. Geopotential height increases when surface pressure increases as the core of a high pressure cells entrains ozone from the stratosphere.

STUDY OF CHANGE IN CLOUD COVER

Cloud comes in all shapes, types, sizes altitudes and density and is notoriously difficult to measure.

At http://www.atmos.washington.edu/~sgw/PAPERS/2007_Land_Cloud_JClim.pdf  we have a paper documenting change in cloud cover and establishing correlations between cloud cover over Europe and the North Atlantic Oscillation, a local manifestation of the the northern annular mode.

Survey of cloud cover change

A POSITIVE CORRELATION OF CLOUD WITH SURFACE TEMPERATURE IN WINTER AND NEGATIVE IN SUMMER??

Note that in the mid latitudes in winter, cloudiness is associated with incursions of warm, moist air from the tropics promoting a positive correlation between the presence of clouds and surface temperature. The band of cloudiness formed by frontal activity occurs in the interaction zone between cold dry air of polar origin and warm air of tropical origin. People  might observe that ‘its too cold to rain’ when the air is coming from high latitudes. Alternatively they might say, they can ‘smell’ the rain coming when the air is humid and it comes from lower latitudes. Or they might say, ‘the temperature will increase when it starts to rain’.

To suggest that the positive correlation between cloud cover and temperature in winter is due to back radiation from clouds or that there is a positive causal relationship between the presence of cloud and surface temperature due to back radiation involves an error in logic. Its warmer in winter when there is cloud about  because the cloud arrives with a warmer, moister body of air that originates in tropical latitudes.  Cloud does not cause warming in winter and an opposite effect in summer. Cloud always involves an attenuation of solar radiation.

CONCLUSION

There should be no confusion as to the effect of cloud on surface temperature. To suggest that the climate is warming due to back radiation indicates a lack of appreciation of the reality of the way in which the atmosphere mediates the flow of solar energy to the surface of the planet and a lack of appreciation of the manner in which the atmosphere actively cools the surface.

To suggest that back radiation is causing warming without first ascertaining that cloud cover has not fallen away indicates an appalling lack of common sense and responsibility.  This brand of ‘science’ is unworthy of the name.

Many sceptics of the AGW argument wrestle with the notion that there is some sense in the idea of ‘back radiation’ from clouds and a CO2 rich atmosphere and try and assess whether the ‘feedbacks’ built into IPCC climate models are an exaggeration of reality. Most unfortunately this belief in cloud radiation feedback and the primacy of a ‘back radiation effect’ has given the ‘anthropogenic’ argument legitimacy.

Back radiation is no defence against a wind chill effect! You wear clothes to combat conduction and convection. To think otherwise is to be muddle headed.

The manner in which the Earth warms and cools indicates that there is another mechanism at work. This other mechanism has primacy and a study of the manner in which the globe has warmed and cooled suggests that it is also a sufficient explanation of the change that has occurred. It is a two way process, capable of warming and cooling as we observe on an inter-annual basis. The mechanism that is responsible for inter-annual variations is also responsible for the decadal and longer trends. When you understand the mechanism you will see that cooling has already begun and more cooling is the immediate prospect.

If you can not explain the inter-annual variations you fail climate 101. UNIPPC, you fail climate 101.

 

Advertisements

4 thoughts on “12 VARIATION IN ENERGY INPUT DUE TO CLOUD COVER

  1. An excellent over view, as usual Earl. To be picky, perhaps the first sentence should say 90% mass….for scientific clarity. Meanwhile, the CAGW boffins try to analyse anomalies the relative size of pin pricks. Nice to re focus on the elephant.

    Like

  2. Macca, I live in dread of getting the maths wrong. 10 in 100 is 10% . 10 in 1000 is 1%. If its 1000 hPa at the surface then 10 hPa has just 1% of 1000 above that point. 10 hPa is at 30 km elevation.

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s