This additional absorption is due to surface minerals with lower emissivities than the atmospheric dust. Figure 3 and Figure 4. These figures show daytime Martian surface temperatures. During the day, surface temperatures are similar in the mid-latitudes of the planet, regardless of albedo, in contrast to nighttime temperatures . This difference is a result of the differing thermal properties of the surface materials, which are emphasized at night.
Small particles lose their heat quickly at night, while rocks stay warmer longer.
The view in Figure 3 shows the large extent of the winter south polar cap. The white area near the equator on the right side of the image is Syrtis Major, a low albedo feature on the surface. Below Syrtis Major is a semi-circular region of cooler temperatures that are in the northern portion of the Hellas basin. A triangular white area to the left of Syrtis Major is another low albedo region, Sinus Meridiani. Figure 4 shows the warmer north polar region, where it has been summer and is now approaching the fall season.