Source: Popular Science China
Temperature is the temperature of the air. From a physical perspective, temperature is a physical quantity that indicates the degree of cold and cold air, and is a measure of the average kinetic energy of air molecules. The temperature mentioned in general in life refers to the temperature in the louver box used in meteorological observation at a height of 1.5 meters above the ground. This temperature basically reflects the temperature at the observation location (local).
Source: Visual China
1. What exactly is the temperature?
In the 1830s, British botanist Brown observed with a microscope that pollen moves endlessly on the water surface, which is the well-known Brownian movement. People also found that the higher the temperature, the more intense the Brownian movement will be when heated to a solution containing solid particles. The same is true for air. When air obtains heat, its molecular average kinetic energy increases and the temperature increases; conversely, when air loses heat, its molecular average kinetic energy decreases and the temperature decreases accordingly.
People usually use atmospheric temperature to indicate the degree of hot and cold of the atmosphere, which is called atmospheric temperature or air temperature. This is to distinguish it from the soil temperature (soil temperature) and the water temperature (water temperature). If it is not for this difference, if we say temperature, it will not cause people to misunderstand it.
Because the heat of the atmosphere mainly comes from the ground, the properties and conditions of the ground are very different, including oceans and land, mountains and plains, deserts and forests, wet and dry areas, etc., the impact of different ground conditions on atmospheric temperature is also different.
2. The temperature, the ground is mild and the water temperature. It is the most representative difference between
. For example, the solar radiation energy that reaches the ground at a certain latitude is the same, but the results are different. The heat rises sharply on land, but the temperature rises on the ocean is very gentle. Why? After careful analysis, there are at least the following reasons:
First, the reflectivity of on land is greater than that of the ocean water surface, resulting in the actual solar radiation absorbed by land 10% to 20% less than that of the ocean. For this reason, the land should heat up more than the ocean, and cool faster than the ocean.
Second, the land is not transparent to solar radiation of various wavelengths, and the absorbed solar radiation is used on the surface of the land that is heated very thin. Although the water surface is opaque to red light and infrared rays, it is transparent to the rest of the visible light and the ultraviolet rays reaching the water surface. This part of the radiation energy can reach the depths of the ocean.
Third, rocks and soil are both bad conductors, and there is very little heat transmitted to the underlying layer of the soil. On the contrary, water has high conductivity and the obtained solar radiation energy quickly conducts to the lower layer.
Fourth, rocks and soil cannot flow up and down, left and right, but waves, ocean currents and convections are on the ocean to transport heat horizontally and exchange heat vertically.
Fifth, the specific heat of rocks and soil is smaller than the specific heat of water. The specific heat of rocks is about 0.8368 jug/g·de; the specific heat of water is 4.184 jug/g·de. If the heat of 4.184 coke is given to 1 gram of water, the temperature can be increased by 1 ℃; if the heat of 4.184 coke is given to 1 gram of rock, the temperature can be increased by 5 ℃.
The second to fifth reasons are that the solar radiation obtained from land is concentrated only on the surface, causing the ground to heat up rapidly and violently, thereby enhancing the sensational heat exchange between the ground and the atmosphere. The water surface spreads part of the solar radiation to the lower layer, causing the water temperature to continue to rise, and the heat sensation transmitted to the atmosphere naturally decreases.
Sixth, the sea surface has sufficient water supply, strong evaporation, consumes a lot of heat on the water surface, making the water temperature not high, and reducing the sensational heat exchange of the air, but the heat is mostly brought into the atmosphere in the form of latent heat. Sensing heat is the heat that can be felt, which can immediately increase the temperature; latent heat cannot heat up for the time being. Only when the water vapor condenses can the latent heat be released and the atmosphere can be heated.
It can be seen from this that even under the same solar radiation conditions, there is still a big difference between ground temperature and water temperature.Their atmospheric heat exchange methods (whether it is sensation or latent heat) and quantity are different, resulting in differences in weather and climate.
The difference in weather and climate on the earth does not only occur between oceans and land, even if it is on land, deserts and forests, wastelands and farmlands, dry and wet areas, windward and leeward slopes, sunny and shade slopes, etc., the weather and climate are also different. However, to a certain extent, it is related to dry or wet ground.
The dry ground is closer to the general land surface than the dry ground, and the wet ground is closer to the water surface, but the difference is not as prominent as the comparison between land and ocean.
3. The secret of warm winter and cool summer and cold winter and hot summer
We already know that there are great differences in the temperature of the ocean and land. The ocean has a great function of regulating temperature. When the solar radiation is strong, the ocean can absorb most of the radiant heat and store a large amount of heat through heat exchange inside the seawater. When solar radiation weakens, the ocean can release the stored heat again.
Therefore, compared with land, the ocean is characterized by warm winter and cool summer. The land is cold in winter and hot in summer. The distribution of sea and land on the surface of the earth is very uneven. The land area in the northern hemisphere is about twice the size of the southern hemisphere, and the ocean area is smaller than that in the southern hemisphere. Therefore, the northern hemisphere is hotter in summer than in the southern hemisphere and colder in winter than in the southern hemisphere. The average temperature in the northern hemisphere is 22.4℃ in summer, only 17.1℃ in the southern hemisphere, the average temperature in winter is 8.1℃ in the northern hemisphere, but 9.7℃ in the southern hemisphere.
has a significant impact on high-latitude continents in winter than in summer. The continent cools sharply in winter, but the temperature rises very much in summer. For example, near latitude 40°, the coastal Tianjin was -4.0°C in January, which dropped to -8.1°C (corrected to sea level), a total of 4.1°C, while in July, it was 26.4°C, and in Hohhot rose to 27.9°C, only 1.5°C.
At low latitudes, the mainland's impact is significant in summer than in winter. In summer, the mainland's heating is drastically, but the winter cooling is not much. For example, near 30° north latitude, the temperature in Hangzhou, Zhejiang in July was 28.4°C and Wuhan, Hubei in total increased by 0.4°C, while in January it was 4.1°C. The influence of sea and land has different effects between different latitudes, indicating that the ocean's regulating temperature is different at different latitudes and seasons.
Produced by: Popular Science China
Author: Meteorological Wanqian Popular Science Team
Producer: China Popular Science Expo
Editor in charge: Hu Huiwen
Forward: Wei Shujing
Review: Hao Lin
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