Source: WeatherSTEM
As the sun rises each day, incoming solar radiation increases on the land and water. As radiation warms the ground, the air just above the surface is warmed through conduction and begins to rise as a “thermal” into the atmosphere. In the afternoon, solar radiation begins to decrease as the sun sinks lower on the horizon. The highest temperatures of the day normally occurs an hour or two before the net radiation reaches zero. The exact time of the highest temperature is dependent on a variety of factors including clouds, soil, vegetation, bodies of water, evaporation and seasons. At night, Earth’s surface and air lose more energy than they receive and start to cool.Radiational cooling is when both the ground and the air that is in contact with the ground, radiate infrared energy back into the atmosphere. As night progresses this transfer continues until the coldest air is found near the ground. Wind and moisture can slow this process, while snow is a good infrared emitter and can increase the radiative process. Low temperatures, including the minimum temperature, can occur just before or just after sunrise.