Final answer:
The large changes in temperature in the temperate desert are caused by low humidity and the absence of cloud cover. Clear skies allow for intense heating during the day, but without moisture or clouds to retain heat, temperatures drop quickly at night.
Step-by-step explanation:
In the temperate desert, the large changes in temperature between day and night are primarily caused by two factors: low humidity and the absence of cloud cover. During the day, the sun's rays heat the ground directly because of the high angle of sunlight incidence in these latitudes and the generally clear skies. The lack of significant moisture in the air allows the sun's energy to be more intensely focused on the surface, leading to higher daytime temperatures.
However, at night, without the insulating effect of a cloud layer and due to the dry conditions, the heat rapidly dissipates into the atmosphere. The low humidity is significant because water vapor in the air holds onto warmth and without it, there is no mechanism to retain the day's heat. This phenomenon leads to a significant drop in temperature when the sun goes down. This contrast is responsible for the characteristic extreme temperature fluctuations often found in desert climates.