Connotation of solar radiation curve

Temporal and spatial variation characteristics of astronomical radiation

① In a year, the equatorial radiation is the most and the polar radiation is the least. This uneven distribution of heat will inevitably lead to the difference of temperature at various latitudes on the earth's surface, and tropical, temperate and cold climate will appear on the earth's surface;

② Astronomical radiation is larger in summer and smaller in winter, resulting in higher temperature in summer and lower temperature in winter. Atmospheric attenuation of solar radiation includes absorption, scattering and reflection of solar radiation by the atmosphere. When solar radiation passes through the whole atmosphere, almost all ultraviolet rays below 0.29μm are absorbed, and the atmospheric absorption is very small in the visible region.

There is a strong absorption band in infrared region. The main substances that absorb solar radiation in the atmosphere are oxygen, ozone, water vapor and liquid water, followed by carbon dioxide, methane, nitrous oxide and dust. Clouds can strongly absorb and scatter solar radiation and also strongly absorb solar radiation reflected from the ground. The average reflectivity of clouds is 0.50 ~ 0.55.

The influencing factors of solar radiation are as follows:

1. Latitude position: low latitude makes the high angle of the sun at noon large, and the distance of solar radiation passing through the atmosphere is short, so it is less weakened by the atmosphere, so the solar radiation reaching the ground is strong; On the contrary, it is weak. This is also one of the reasons why solar radiation decreases from low latitude to two poles.

2. Weather conditions: On sunny days, due to the few and thin clouds, the atmosphere has a weak weakening effect on solar radiation, and the solar radiation reaching the ground is strong; In rainy weather, due to the thick and many clouds, the atmosphere has a strong weakening effect on solar radiation, and the solar radiation reaching the ground is weak.

For example, the equatorial low pressure in the equatorial region controls rainy weather and the subtropical high pressure controls sunny weather, so the solar radiation in the equatorial region is weaker than that in the subtropical region.

3. Altitude: the altitude is high, the air is thin, and the atmosphere has a weak weakening effect on solar radiation, so the solar radiation reaching the ground is strong; On the contrary, it is weak. This is the main reason why the Qinghai-Tibet Plateau has become the region with the strongest solar radiation in China.

4. Sunshine length: long sunshine time, strong solar radiation, short sunshine time and weak solar radiation. In the summer half year, the days at high latitudes are long, which makes up for the energy lost at low solar altitude.

5. Atmospheric transparency: High atmospheric transparency has little effect on weakening solar radiation, which makes the solar radiation reaching the ground very strong.

6. Degree of air pollution: The heavier the air pollution, the weaker the solar radiation, and the less the solar radiation reaching the ground.