Kerry, I got onto cloudiness as a major impact on greenhouse effect living in Antwerp in 1987/1988/1989. As DJ said, contrails are blocking the sun, reflecting light [and therefore heat] back out.
In Antwerp, which is usually cloudy due to natural nasty weather, even bright, sunny days are dull. The sky gets covered with diffused contrails with insolation reduced by, I guess, about 60%. I took a photo it was so impressive one day. There's a constant stream of high-flying aircraft over the area.
At the time, ozone depletion was also a concern and I wondered whether BP could develop "Jetozone" which would be a catalyst for production of ozone to be included in jet fuel. Part of my job was to come up with fuel technology, though that was a bit out of my realm. I didn't take it far - not even to the extent of figuring out what would do the job, if anything. Just as CFCs catalytically destroy ozone, I wondered whether some antidote could be deployed.
Because Earth has been climatically stable for eons, with correction effects gaining as ice-ages or warm periods gain ground, it seems that the interplay of clouds, snow, CO2 levels, plants and animals is what maintains climate stability [within the wide variation between ice age and warm periods], sufficient to keep the whole show on the road].
Sunspots, bolide impacts and other extraterrestrial effects, as well as volcanic activity, and rising and falling sea levels also have an effect, but biggies on a day to day basis are cloud, snow and plants. The animals go along with the plants and move pretty quickly.
I wonder what the distribution of clouds is by latitude. Modeling cloud activity must be a challenge. I suppose cameras in space monitor cloud cover constantly, so the data should be available.
As Earth cools, or heats, clouds would predominate in particular latitudes. As that predominant latitude, the cloud cover centre of area, moves north or south, the proportion of Earth covered with cloud would shrink or expand, as there is a lot more circumference at the equator than nearer the poles.
As the cloud centre of area nears the equator, the amount of light reflected would increase, cooling the Earth, so that the cloud would shrink back towards the poles. Depending on humidity and all the other variables. A warmer Earth must make more cloud. I guess there is plenty of data on that since every year we get winter and summer and more or less cloud as a result.
I should ask Google about cloud variation.
Mqurice |
