What is the weather symbol?
Terminology commonly used in weather forecast
Sunny day: the cloud cover in the sky is less than 30%.
Yin: The amount of clouds in the sky accounts for more than 90%.
Fog: A large number of tiny water droplets or ice crystals float in the air near the ground, and the horizontal visibility drops below 1 km, which affects transportation.
Light rain: the daily precipitation is less than 10 mm.
Heavy rain: the daily precipitation is 25.0-49.9mm..
Thunderstorm: Intermittent precipitation accompanied by lightning and thunder.
Hail: With the violent vertical movement in the cumulonimbus cloud, small hail nuclei repeatedly rise, condense, fall and melt, and grow into small ice cubes with transparent layers, which have an impact on crops.
Freezing rain: raindrops freeze on the ground below 0℃, also known as rain song (frozen by fog drops, called rime), which often falls off the power lines, freezing the road surface and affecting communication, power supply and traffic.
Sleet: The temperature near the ground is slightly higher than 0℃, and wet snow or rain and snow drop at the same time.
Xiaoxue: The daily snowfall (melting into water) is less than 2.5mm. ..
Medium snow: the daily snowfall (melting into water) is 2.6-4.9 mm.
Heavy snow: the daily snowfall (melting into water) reaches or exceeds 5.0 mm.
Frost: Frost is formed when water vapor condenses into white crystals on the ground and the surface of objects at a temperature below 0℃. If there is little water vapor and no frost, it is said that black frost has freezing damage to crops, which is called frost.
Low-pressure trough and high-pressure ridge: on the fluctuating high-altitude westerly airflow, the trough corresponds to the low-pressure trough, with active warm air in front of the trough, rain and snow weather, controlled cold air behind the trough, and strong wind cooling weather; The peak corresponds to the ridge of high pressure and the sky is clear.
Cold and warm fronts: A cold front is the front of cold air. At the junction of cold air and warm air mass, cold air pushes towards warm air. It is windy and rainy on the cold front, and windy and cool after the front; On the contrary, it is a warm front, the front is rainy, and it turns cloudy and sunny after the front, and the temperature rises.
Strong wind: expressed by wind vector, consisting of wind mast and wind plume. The wind pole refers to the direction of the wind, with eight directions. The wind plume is represented by 3 or 4 short strokes and triangles, perpendicular to the right side of the wind pole end (northern hemisphere).
Important tool
The important tool of weather forecast is weather map. Weather maps are mainly divided into ground and high altitude. The weather map is densely covered with various weather symbols, which are filled in after being translated according to meteorological codes all over the country.
Each symbol represents a particular weather.
The symbols representing clouds are Cirrus, cirrocumulus, cirrostratus, Altocumulus, nimbostratus, Cumulonimbus and so on.
Symbols representing weather phenomena include: thunderstorm, tornado, fog, continuous heavy rain, light snow and light showers.
In addition, there are symbols indicating the change of wind direction, wind speed, cloud cover and air pressure.
All these symbols are filled in their respective geographical positions in a unified format. In this way, meteorological elements such as wind, temperature, humidity, air pressure, clouds, cloudy, sunny, rain and snow observed at the same time in a wide area can be filled in a weather map. So as to form weather maps representing different times. With these weather charts, forecasters can further analyze and process them, and express the analysis results with lines and symbols of different colors.
The analysis content of the ground weather map includes: drawing the regional scope of important weather phenomena (such as precipitation, gale, blizzard, etc.). ), draw the positions of cold front, warm front and quasi-static front, draw the isobar of the whole picture, and mark the center and intensity of low pressure and high pressure. Through this analysis, we can clearly see the atmospheric pressure at that time: where is the high pressure, where is the low pressure, and where is the confrontation zone between cold and warm air.
The meteorological element filled in the high-altitude weather map is the height of each point on the same isobar surface, so the contour lines separated by a certain value are analyzed and drawn. After the contour line is drawn, we can see the pressure situation at that time: where is the trough of low pressure and where is the ridge of high pressure. Then draw an isotherm and mark the cold and warm center. From the configuration of heating and cooling center, low pressure trough and high pressure ridge, forecasters can make a general judgment on the future air pressure situation.
With the development of meteorological science and technology, some meteorological stations have used advanced detection tools and forecasting methods such as meteorological radar, meteorological satellites and electronic computers to improve the level of meteorological forecasting and achieved remarkable results. It is reported that since 1966, typhoons in tropical oceans around the world have almost never escaped the "eyes" of meteorological satellites. Satellite cloud images play an important role in monitoring and early detection of severe storms and severe disastrous weather.
(Reference:
Baidu Encyclopedia: Weather Forecast)