User:Mcarst/sandbox

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= High Cloud Feedback = The high cloud feedback is defined as the change of high cloud properties (e.g. height, opacity, coverage) due to global warming which amplifies or weaken the warming. It is one part of the Cloud feedback which is an important variable in the climate system. This Feedback is the reason for a large part of the uncertainty of todays climate models.

The cloud feedback, and therefore also the high cloud feedback, has a longwave and shortwave part which are summed up to get the total feedback. The longwave part is the describing the interaction of the clouds with the longwave radiation coming from the earths surface. The shortwave feedback on the other hand is the interaction of the clouds with the shortwave radiation coming directly from the sun.

what properties are longwave and pos/neg + the same for the shortwave

The main influences on the feedback are the global coverage and the cloud temperature change with height.

Physical Background

 * how basic does this need to be? shortly introducing feedback in general?

Box 2 :


 * clouds interacting with radiation is measured with the difference of the radiative flux between all-sky (with clouds) and clear-sky (without clouds) measurements
 * negative shortwave feedback by reflecting radiation upwards
 * positive longwave feedback by reducing the outgoing longwave radiation (absorption, reflection,...)
 * feedback proportional to cloud amount but also influenced by altitude and optical depth
 * not spatially homogeneous!


 * heating = warming

Longwave Feedback

 * dominated by the cloud altitude
 * FAT (vs PHAT) as positive --> how much the main amount globally happening
 * increases also with optical depth

Shortwave Feedback

 * increases with optical thickness
 * only slightly influenced by the cloud height.

Conclusion
More research has to be done, model solutions (own section?)