Venus atmosphere variation in temperature

This is a map showing the changes in temperatures in Venus’ atmosphere with altitude at different latitudes. The maps have been obtained with radio from the VeRa instrument on ESA’s Venus Express orbiter.

It is obvious that the day-side is hotter than night-side at low as well as high altitudes, because of solar energy absorbed by the clouds.

The day-time temperature increases by about 30–40 degrees from the south pole to the equator at altitudes below 60 km. This shows that clouds absorb more solar radiation at the equator than at the poles. This contrasts to the roughly constant night-time temperature below 60 km.

It appears that there is a day–night equatorial temperature difference that reaches about 40 degrees at 55 km altitude. The ‘cold collar’, a temperature depression encircling the pole in both hemispheres, is clearly observed on both the day-side and the night-side between 60° and 80° latitude at 63km altitude. The collar extends to 40° latitude during the night in the southern hemisphere.