What is the root cause of climate formation and change, and it is also the energy of climate system?

A: Solar radiation is the fundamental cause of climate formation and change, and it is also the energy source of the climate system.

First, the sun transmits energy in the form of electromagnetic waves, which is called solar radiation. It refers to the electromagnetic waves and particle streams emitted by the sun into space. The energy transmitted by solar radiation is called solar radiation energy. The distribution of solar radiation energy according to wavelength is called solar radiation spectrum. (0.4~0.76μm is the visible region, with energy accounting for 50%; Above 0.76μm is the infrared region, accounting for 43%; The ultraviolet region is less than 0.4μm, accounting for 7%)

The solar radiation energy received by the earth is only 1/2 of the total radiation energy emitted by the sun into space, but it is the main energy source of the earth's atmospheric movement.

Second, the basic information

Third, solar radiation.

Solar radiation is the main source of energy on the earth's surface. The distribution of solar radiation in the upper atmosphere is determined by the astronomical position of the earth and is called astronomical radiation. The climate determined by astronomical radiation is called astronomical climate. Astronomical climate reflects the basic outline of the spatial distribution and time change of global climate.

Solar radiation changes regularly with seasons, forming four seasons.

Besides the change of the sun itself, the astronomical radiation energy mainly depends on the distance between the sun and the earth, the altitude angle of the sun and the length of a day.

The earth's orbit around the sun is elliptical, and the sun is located in one of two focal points. Therefore, the distance between the sun and the earth has been changing. Every year165438+ passes through perihelion from October 2nd to 5th and apohelion from July 3rd to 4th. The intensity of solar radiation received on the earth is inversely proportional to the square of the distance between the sun and the earth. The angle between the sun's rays and the ground level is called the solar altitude angle, which changes every day and every year. When the solar altitude angle is large, the solar radiation is strong.

The length of a day refers to the length of time from sunrise to sunset. The sunshine length of the four seasons on the equator is 12 hour, and the four seasons outside the equator change. At 23.5 north latitude, the sunshine duration in the vernal equinox and autumnal equinox is 12 hours, and the sunshine duration in summer solstice and winter solstice is 14 hours, 5 1 minute and 9 hours and 09 minutes respectively. Extreme days and nights occur at latitude 66 33'. The winter and summer seasons in the northern hemisphere and the southern hemisphere are just the opposite.

The temporal and spatial variation characteristics of astronomical radiation are as follows: ① The equator gets the most radiation and the polar regions get the least radiation. This uneven distribution of heat will inevitably lead to the difference of temperature at various latitudes on the earth's surface, and there will be tropical, temperate and cold climates 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.