Night Clouds Warm Red Planet

Daytime clouds on Mars are believed to be 62 miles above the surface, which (amazingly) makes them the highest clouds discovered so far on any planet. These daytime clouds are easier to spot than the nighttime clouds because they are cooler than the Martian surface and therefore easier to read thermally. But at night the surface temperature drops, making the temperature difference between the clouds and the planet less defined; therefore, the clouds are much more difficult to spot. Nighttime clouds have recently been detected (for the first time) because researchers have noticed a temperature anomaly during the nighttime in which the temperature in some areas does not drop as much as it is expected to. The study ultimately showed that regions covered by clouds at night on Mars were 35 degrees (F) warmer than those not covered.

http://www.space.com/scienceastronomy/070206_st_mars_clouds.html