A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).


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For Discussion: Can convection neutralize the effect of greenhouse gases?

Here’s an idea for commenters to sink their teeth into — Stephen Wilde postulates a mechanism where convection can neutralize the effect of changes in  greenhouse gases. The focus in David’s series of blog posts has been on radiation, but the troposphere is governed by convection.  The tropopause is the boundary where convection runs out of oomph, and above the tropopause, in the stratosphere, radiation rules supreme. Airliners like to fly at the bottom of the stratosphere (“thirty thousand feet”), just above the convection and water vapor in the troposphere, because it’s calm. But sometimes turbulence from the troposphere punches up into the stratosphere, so think of Fig 1 below if you are asked to suddenly sit in your seat and fasten your seat belt.

All the focus on radiation imbalances tends to ignore the powerful effects of gravity and convection. To get a sense of how important gravity is, ponder that a mere 3km above the surface the pressure is 300hpa lower, but gravity stops  the surface air from rushing up and equalizing that. Imagine if there were two sites on the ground where pressure was, say,  1000hpa and 700hpa, and they were only three kilometers apart, we’d [...]