Why is it hottest at 2 pm?

At noon 12, the solar radiation is the strongest. Sunlight shines vertically on the ground, making it hot. The heat absorbed by the ground releases dry air, so it takes some time to heat up. It was not until two or three o'clock in the afternoon that the ground temperature rose to the highest and the temperature was the highest. At this time, although the sun sets in the west, the altitude angle is still very large, and the heat stored on the surface is still greater than the heat released, which makes the temperature continue to rise, the local surface heat balance, and the surface temperature reaches its peak. After that, the surface releases more heat than the stored heat, which reduces the surface temperature.

Whether the weather is hot or cold mainly depends on the atmospheric temperature, and the main factor affecting the atmospheric temperature is the heat given to the atmosphere by the sun. But direct sunlight is not the main reason for the temperature rise. Air can only absorb about 14% of the direct sunlight heat, and about 43% of the heat is absorbed by the ground. When the ground absorbs the heat of the sun, it is conducted into the air through radiation, convection and other forms, which is the direct cause of the temperature rise.

Similarly, after the sun went down, the atmosphere lost its heat supply and began to dissipate heat continuously. If an object radiates heat instead of absorbing it, the temperature is of course getting lower and lower. When the sun rises again, the sun can provide heat to the ground and the ground can provide heat to the atmosphere. When the atmosphere receives more heat than it emits, the temperature can rise again. Now you understand! Early morning is the coldest time. If you or your family want to exercise in the morning, don't wait until the sun comes out to warm the atmosphere!

In meteorology, the physical quantity representing the degree of air heat and cold is called temperature, which is referred to as temperature for short. The international standard unit for temperature measurement is Celsius (℃).

The temperature mentioned in the weather forecast refers to the air temperature measured in the open air without direct sunlight (usually measured by blinds). The highest temperature is the highest temperature in a day, generally appearing in14-15; The lowest temperature is the lowest temperature in a day, usually before sunrise.

Temperature records can characterize the thermal characteristics of a place, which is indispensable in both theoretical research and the application of national defense and economic construction. Temperature is one of the conventional measurement elements in ground meteorological observation. The temperature has a fixed temperature (the basic station observes four times a day, and the four hours are 02, 08, 14 and 20 respectively; According to the actual situation, some stations observe three times a day, at 08: 00, 14 and 20: 00 respectively. Reference station observation 24 times a day), as well as the daily maximum and daily minimum temperature.