China Naming Network - Almanac query - How to read satellite cloud images of weather forecast? How do you know if it will rain or be sunny?

How to read satellite cloud images of weather forecast? How do you know if it will rain or be sunny?

Meteorological satellites are geostationary satellites, positioned on the equator, with a fixed altitude and relatively stationary with the earth. Geostationary satellites use infrared detectors to detect the earth's surface temperature. If there are clouds, it is considered to be the temperature of the detected clouds. The infrared detector detects at step angles and line scanning angles along the longitude and latitude lines, and each scanning angle is 140 microarcs. However, although the step angle and line scan angle of the scan are uniform, the longitude and latitude coordinates corresponding to the earth are not evenly distributed. A weather satellite cannot detect the temperature at all points on the earth, and the Antarctic and the North Pole are also blind spots. Therefore, the one-to-one correspondence between each scanning point and its longitude and latitude is generally calculated first, and then the temperature data detected by the infrared detector (the infrared detector converts the temperature into grayscale, that is, black and white with different shades of color), The two sets of data are combined and synchronized to the two-dimensional map, which is the satellite cloud image we see. White generally represents low temperature areas, black represents high temperature areas, and white areas represent clouds. General weather prediction is not judged from a single satellite cloud image, but from the movement and changes of clouds (wind vectors) at continuous moments. That is to say, a cloud image cannot play a role in weather prediction. Use image matching to continuously compare the small range of pixels (such as 4X4) corresponding to the gray matrix within a certain range (such as all 4X4 within 16X16) to determine the wind vector, the size and direction of the wind, and pass through the clouds movement to determine weather changes. This kind of calculation is usually relatively large, so the weather bureau must generally have something as abnormal as a supercomputer.