Space Forum / Space Flight / July 2009

Gravity and density of that atmosphere.  But it's likely that solar
radiation may have split hydrogen compounds and eroded away the
liberated hydrogen, contributing to the existing conditions.

--Damon

Last month's Sci Am (I think) has an article on planetary atmospheres, what
causes them to be lost, kept, etc.  Suggest looking there.

“The Unexpected Temperature Profile Of Venus's Atmosphere”
http://www.spacedaily.com/reports/The_Unexpected_Temperature_Profile_Of_Ven
us_Atmosphere_999.html
The only problem being with some of this graphic applied eye-candy
analogy is that so little of the solar energy actually reaches unto
the lower (below cloud) atmosphere and directly touches the
geothermally heated surface.

“Jean-Loup Bertaux, Service d'Aeronomie du CNRS, France, Ann-Carine
Vandaele, Institut d'Aeronomie Spatiale de Belgique, and colleagues
have now used Venus Express to discover an unexpectedly warm layer of
air on the planet's night-side. It sits between the altitudes of
90-120 km, a region that is generally so cold at night that scientists
often refer to it as Venus's cryosphere. The new measurements show
that the temperature excess ranges from 30 to 70C and peaks at an
altitude of 100 km.” (it’s unlikely their reporting error will be
corrected before getting extensively published in public science
journals and textbooks as is) Venus - night-time temperatures in the
atmosphere
http://www.esa.int/esaMI/Venus_Express/SEM5A373R8F_0.html
http://www.esa.int/esaMI/Venus_Express/SEM5A373R8F_1.html#subhead1

This following image/graphic of the Venus day/night thermal profiles
is even a little more intriguing to those of us interested in the
future prospects of our accomplishing Venus without getting our
composite rigid airship unnecessarily fried in the process.
http://www.esa.int/images/Picture5_H.jpg

~ BG