The basic formation of weather forecast needs several steps.

Modern weather forecast has five components:

1, collecting data

The most traditional data are data such as air pressure, temperature, wind speed, wind direction and humidity collected by professionals, enthusiasts, automatic weather stations or buoys on the ground or at sea. The World Meteorological Organization coordinates the timing of these data collections and sets standards. These measurements are made every hour (METAR) or every six hours (SYNOP).

Data from meteorological satellites are becoming more and more important. Meteorological satellites can collect data from all over the world. Their visible photos can help meteorologists study the development of clouds. Their infrared data can be used to collect the temperature of the ground and cloud top. By monitoring the development of clouds, we can collect the wind speed and direction at the edge of clouds. However, because the accuracy and resolution of meteorological satellites are not good enough, ground data is still very important.

2. Data assimilation

In the process of data assimilation, the collected data are combined with the numerical model used for prediction to produce meteorological analysis. The best estimate of its atmospheric state is the three-dimensional representation of temperature, humidity, air pressure, wind speed and wind direction. ?

3. Data weather

According to the results of physics and fluid mechanics, the change of atmosphere with time is calculated.

4. Output processing

The original output of model calculation generally needs to be processed to become a weather forecast. These treatments include using statistical principles to eliminate the deviation in known models or making adjustments with reference to the calculation results of other models.

5. Production process

According to the information provided by the relevant departments, the national meteorological situation map (that is, the background map of the weather forecast program) is made on the computer; The host stood in front of a blue screen and "pointed" to explain the weather (how to grasp the location of each area, the host has only one secret-rote memorization); The film and television center synthesizes images and uses charts instead of blue screens on the computer; The film and television center transmits the completed program to CCTV.

Extended data

When listening to the weather forecast, we often hear time terms such as "today's day" and "tonight", and meteorological terms such as "cloudy", "cloudy" and "sunny".

"Today's daytime" refers to 12 hours from 8 am to 20 pm; "Tonight" means 12 hours from 20: 00 to 8: 00 the next morning. "Clear" means that the cloud cover accounts for10-30%; "Cloudy" means that the amount of clouds accounts for 40-70%; "Yin" means that the cloud cover accounts for 80- 100%.

Meteorological units have two standards for precipitation: 12 hours and 24 hours. /kloc-the standard of 0/2 hour precipitation level is: "light rain" refers to the precipitation of 0.6-5 mm; The "moderate rain" precipitation is 5.1-15 mm; "rainstorm"15.1-30 mm; "Rainstorm" is 30.1-70mm; The rainstorm is 70. 1-200mm.

The standard of 24-hour precipitation level is: "light rain" precipitation means1-10mm; The precipitation of "moderate rain" means10.1-25mm; "Rainstorm" precipitation means 25. 1-50 mm; "Rainstorm" means 50.1-100 mm; "Rainstorm" is the precipitation of 100. 1-250 mm, and the forecast time does not exceed 12 hour, which means the precipitation level standard of 12 hour.

If it is predicted that there will be rain and snow during the day or night today, it means the snowfall within 12 hours. If it is predicted that there will be moderate to heavy snow from day to night today, it refers to the precipitation within 24 hours. In addition to 12.24 hour forecast, there are 48 hour forecast, 72 hour forecast and future weather analysis.

Because the weather bureau only provides three forecasts to TV stations, radio stations and major newspapers a day: morning, noon and evening. If you can't make a timely forecast of the sudden change of weather, how can you know the sudden change of weather in time? Since September 2009, China has opened a meteorological hotline 12 1.

There is a new forecast every two hours on average, which is timely, accurate, convenient and fast. For example, Yangzhou's meteorological hotline 12 1 can answer 60 calls at the same time, and the phone bill is the same as that of ordinary local calls. Most urban meteorological stations (bureaus) open the official meteorological Weibo.