Have you seen greenhouses built-in cold country yet? In it, people grow flowers. In the countryside, you can also see farmers making plastic-covered houses used to grow vegetables or grow flowers. Use glass or plastic film to build closed rooms that are both light and able to keep the temperature. Even if winter is raining or freezing, the room is as warm as spring.
The Earth we live in is a big greenhouse. Carbon dioxide in the atmosphere insulates and allows sunlight to shine. Sunlight is produced by light waves of different lengths, short wavelengths. When the Sun radiates to the Earth, ozone in the atmosphere will absorb the ultraviolet rays in solar radiation. In contrast, water vapor and carbon dioxide in the air will absorb the infrared rays of sunlight, only light. Only one-third of the heat is reflected in the air; the rock and water absorb the other two. As the ground cools, visible light re-emits long-wave thermal radiation (called infrared radiation) into the air.
Carbon dioxide has the property of almost completely visible light, but long-wave infrared rays, especially those with wavelengths between 12 m and 18 m, are strongly absorbed. Thus, carbon dioxide in the air layer close to the ground acts as glass or plastic in a warm room, light can shine into the room, but the heat cannot diffuse out. This effect causes the air temperatures above the ground to rising, known as the “greenhouse effect.”
If the Earth is like the Moon, there is no air or water, then during the day the Sun falls on the ground, the temperature will reach 127 ° C and cold night down to -183 ° C. Humans, and other creatures cannot live.
Normally, the water and carbon dioxide content of the air is fixed. In general, the carbon dioxide content is three parts per million. But with the strong development of industrial production, many carbon-containing fuels such as coal, oil, gas, etc., have been burned, causing carbon dioxide in the air to increase each year rapidly.
According to the statistic report published by the US World Research Service, 100 years ago, the whole world every year brought into the atmosphere only 96 million tons of carbon dioxide, and today it has increased to five billion tons. It is expected that it will increase by a ladder of eight billion tons in the twenty-first century. The amount of carbon dioxide in the air increases, the stronger the greenhouse effect, and the higher the temperature of the Earth.
Scientists predict that by the end of the twentieth century, the Earth’s temperature will increase by 0.5 ° C. In the next 50 years, if the carbon content in the air doubles, the Earth’s temperature will increase to 3 ° C, which means that the climate of the Earth will become markedly warm. It is an increase in carbon dioxide in the air, causing the Earth’s temperature to rise.