At what time do the highest and lowest temperatures occur in a day?
During the day, the highest temperature is around 2 p.m. and the lowest temperature is around sunrise.
1. The hot or cold weather is mainly determined by the air temperature, and the fundamental factor affecting the air temperature is the intensity of solar radiation. Solar heat is not the main reason that directly increases the temperature. The air directly absorbs only about 14% of the heat energy of sunlight, while 43% of the energy in the visible light region is absorbed by the ground. When the ground absorbs the sun's radiant heat, it is then conducted to the air through radiation, convection, etc. This is the main reason for the rise in temperature.
2. After noon, the solar radiation begins to weaken, but the heat absorbed by the ground is still more than the heat dissipated. Until about 1 o'clock in the afternoon, the ground temperature reaches the highest and the ground radiation also reaches the strongest. Since it takes a certain amount of time for the ground to transfer heat to the atmosphere, the temperature near the ground reaches its highest around 2 p.m., and the atmospheric reverse radiation also reaches its maximum for the day.
3. In the same way, the atmosphere mainly loses heat through reverse radiation and atmospheric radiation. There is no solar radiation to replenish heat until sunrise the next day, so until around sunrise the next day the temperature reaches The lowest value of the day.
Extended information:
Maximum temperature meter
Maximum temperature meter: It is specially used to measure the maximum temperature at a certain time interval. Its structure is on the ball. A glass needle is placed at the bottom and extended straight to the capillary mouth to narrow the capillary mouth. When the temperature rises, the mercury expands and the pressure increases, forcing the mercury to squeeze through the narrow tube and rise. When the temperature drops, there is not enough pressure for the mercury to squeeze through the narrow tube and return to the bulb. The mercury column breaks at the narrow tube, so the top of the mercury column above the narrow tube remains at the temperature that the thermometer has felt in the past period of time. to the maximum temperature indicator, so the maximum temperature can be measured.
Minimum thermometer
Minimum thermometer: It is specially used to measure the minimum temperature at a certain time interval. It uses alcohol as the temperature measuring fluid and puts a vernier in the capillary tube. When the temperature rises, the alcohol expands and can rise beyond the vernier, and the vernier itself can remain in place due to the sufficient friction between the top and the tube wall. When the temperature drops and the alcohol column shrinks to contact the top of the cursor, the surface tension of the alcohol liquid surface is greater than the friction of the cursor against the tube wall, so that the cursor does not break through the top of the alcohol column and uses the surface tension of the liquid surface to drive the cursor downward. . In other words, the cursor can only be lowered, not raised. Therefore, the indication at the far end of the cursor from the ball is the lowest temperature that has occurred within a certain time interval.