On the satellite cloud picture of a certain day, Guangzhou is all gray, indicating what the weather is like in Guangzhou.

Satellite observation of the earth has become an indispensable source of information in today's world. Meteorological satellites photograph the earth's surface from different positions in space, and a large number of observation data are transmitted back to the ground workstation through satellites, and then beautiful cloud images are synthesized. People can not only receive visible light cloud images, but also receive satellite photos of other bands, such as infrared cloud images, by using appropriate photosensitive instruments. At present, the commonly used cloud pictures in TV programs are false color dynamic cloud pictures edited by computer from infrared cloud pictures. On the black and white infrared satellite cloud picture, we can see that some places are white, some places are black, some places are gray and so on. So what do these colors mean? We know that if the surface of the earth is a clear sky area, the infrared radiation information emitted from the ground into space is observed by satellites, and the satellite cloud picture is black and gray. The darker the black, the stronger the ground radiation and the better the weather. When the sky is covered with clouds and rain, the satellite observes the infrared radiation from the cloud top into space, which is white or grayish white. White indicates that the radiation is very weak, the temperature is very low, the cloud system is thick and dense, and the rainfall intensity is also very high. The transition zone between clear sky area and cloudy and rainy area is usually covered by dark gray, gray and light gray clouds, indicating that there are clouds with different thicknesses and no obvious precipitation. On satellite images displayed on TV, the surface and ocean are usually represented by green and blue.