Re: not enough...........a little more......and maybe more?
Posted by Southern Man on May 17, 2002 at 08:45
(209.102.129.238)Re: not enough...........a little more......and maybe more? (KB)
A “thermal” is produced when warm air below becomes unstable and rises through a colder layer above. The rising air is replaced by cooler air. Living close to the ocean we get a “sea breeze” almost every afternoon when the air over the land starts rising and is replaced by cooler air from over the ocean. You have described manmade thermals but they also occur totally naturally.
The instability in the air is reduced when a thermal mixes the air. Manmade features can promote thermals but if they don’t the instability in the air will still cause them to occur somewhere. The instability will build until it is eliminated. You notice fewer thermals over forests only because the instability is being released over manmade features.
As far as thermals having an effect on global warming, they do. A thermal moves warm wet air higher into the atmosphere where it cools. The water vapor condenses forming clouds which reflect more sunlight back into space producing a cooling effect.