Why is the higher the altitude, the closer to the sun, but the lower the temperature?

Nuclear fusion reactions are taking place all the time inside the sun, providing energy for all the stars in the solar system, including the earth. The earth relies on warm sunshine to nourish everything, usher in the birth of life and promote the prosperity and development of living things. In our impression, the closer we are to the heat source, the higher the temperature we feel, such as heating around a stove. The sun is a heat source with great mass. Then, the earth is at a higher altitude near the sun, why is the temperature not getting higher and higher, but lower than that in low altitude areas?

Let's look at several heat transfer methods first.

In our daily life, it is actually a process of heat transfer to measure the temperature change with a thermometer or to directly feel the temperature change with the body. If heat is transferred from one system to another, or from one part of this system to another, then the heat transfer process is realized. The heat transfer and temperature change we see in our daily life are actually just a way of heat transfer.

Heat conduction. Mainly through solid or solid, liquid * * * as a conductive medium to complete heat transfer. The reason of heat conduction is that microscopic particles in an object realize heat transfer from a high-temperature part to a low-temperature part or from a high-temperature object to a low-temperature object by colliding with each other on the basis of thermal motion. Heat conduction transfers heat, not temperature, and temperature is only a scalar, indicating the average kinetic energy of microscopic particles of an object; Heat conduction but not heat transfer? Cold? When you hold the ice in your hand, your hand will cool for a while. Some people say that the cold has shifted, which is not correct. It only transfers heat, and the heat is transferred from your hand to the ice, causing the hand temperature to drop and the ice temperature to rise.

Thermal convection. Thermal convection, like heat conduction, also needs specific substances as heat transfer media, except that heat conduction needs solids, while thermal convection needs liquids and gases. Heat is transferred from one object to another through a medium with flowing characteristics, or from one part of an object to another. This kind of heat transfer process is often encountered in our life, such as boiling water, including the heat transfer of kettle, the heat transfer between water molecules, and the heat convection of water as a liquid; Another example is air convection in atmospheric movement, which is also a typical thermal convection phenomenon. The density of hot air increased slightly, while the density of cold air decreased sharply, resulting in rain, snowfall and other weather.

Thermal radiation. This heat transfer process is completely different from the above two. It does not need the participation of any medium, but the inherent property of the object itself, that is, the microscopic particles that make up the object are constantly moving, and they will produce temperatures higher than the absolute temperature, thus releasing energy in the form of electromagnetic waves. The higher the temperature, the greater the thermal radiation intensity and the shorter the wavelength of electromagnetic wave. The lower the temperature, the smaller the thermal radiation intensity and the smaller the corresponding wavelength. Thermal radiation is the most common way of heat transmission in the universe, which can make the heat emitted by stars spread to far places through the extremely scarce space.

Look at the process of heat reaching the earth from the sun.

The energy released by the sun reaches the earth through the vast space, which is divided into several different stages, and its leading heat transmission modes are also different. Mainly includes:

The first stage: from the surface of the sun to the periphery of the earth's atmosphere. In this process, thermal radiation is absolutely dominant, because the density of matter in space is extremely low, and heat can hardly be transferred in the form of heat conduction and convection. Theoretically, electromagnetic waves in vacuum can bring heat to infinity, but space is not a real vacuum, and it also contains a small amount of gas molecules and interstellar dust, which has certain reflection and attraction to electromagnetic waves. So on the scale of macroscopic distance, the farther away from the star, the less heat will be.

The second stage: after entering the stratosphere. Although the air density in this layer is low, most gas molecules are ionized under the action of solar ultraviolet rays and cosmic rays, and the contents of protons and helium nuclei are high. The energy carried by electromagnetic waves in solar radiation is efficiently converted into the internal energy of ionized gas, so the temperature of the escape layer rises sharply, reaching thousands of degrees, which is the highest temperature part in the earth's atmosphere. However, with the decrease of the height of escape layer, the content of ionized gas is getting lower and lower, and the temperature drops rapidly. When it reached the bottom of the escape layer, the temperature had dropped to more than 50 degrees below zero.

The third stage: after entering the stratosphere. The gas molecules here are still very thin, but the ozone content is gradually increasing. Ozone can strongly absorb ultraviolet rays in solar radiation, thus increasing internal energy and temperature. In the stratosphere about 60 kilometers above the ground, a temperature peak is reached, but the absolute temperature of this peak is lower, which is relative to other regions.

The fourth stage: after entering the troposphere. Because this part of the atmosphere is close to the ground, the heat obtained mainly depends on the long-wave radiation of the ground, not the thermal radiation of the sun. Therefore, the higher the distance from the ground, the lower the effect of long-wave radiation on the ground and the lower the temperature. Generally, the temperature drops by 0.6 degrees Celsius per 100 meter.

The main factors that determine the temperature.

From the above analysis, it can be seen that for any system, the factors that determine its temperature mainly depend on the value of heat transfer it accepts. How much of this value is the comprehensive effect of three heat transfer modes: thermal radiation, thermal convection and thermal conduction. Therefore, the radiation intensity, distance of heat source and the material composition of the system are the most critical factors to determine the temperature of the object. For the earth:

The change of solar radiation intensity can be ignored, and the heat released by the sun itself is almost unchanged at the existing time scale.

Small changes in the distance from the sun, such as differences in altitude, perihelion and apohelion in different regions, will make the distance between regions where the temperature is measured different, but this difference can be ignored compared with the average distance between the earth and the sun (654.38+0.496 million kilometers).

The material composition of the earth system affects the earth's temperature, mainly from the difference in the distribution and composition of the earth's atmosphere, which is the most direct and main reason for determining the vertical change of the earth's temperature. The promotion of temperature change in the vertical direction mainly depends on the radiation intensity of two aspects, one is the short-wave radiation of the sun, and the other is the long-wave radiation of the ground. Among them, the troposphere near the ground mainly absorbs long-wave radiation from the ground, which is absorbed by gas molecules and converted into molecular internal energy to achieve the purpose of heating and maintaining temperature.

In summary

The higher the altitude of the earth, the lower the temperature, mainly because of the layered structure of the atmosphere. Even at the highest altitude, the mountains on the ground are in the troposphere. The higher here, the thinner the gas molecules, and the lower the total amount of thermal radiation received and converted into internal energy. At the same time, the thermal radiation that gas molecules in the troposphere can receive mainly comes from the long-wave radiation of the earth, which leads to the phenomenon that the higher the troposphere, the lower the efficiency of receiving long-wave radiation and the corresponding decrease in temperature.