The significance of weather forecast symbols

Special symbols representing various weather phenomena, clouds and sky conditions. Includes weather phenomenon symbols for observation and recording and weather graphic symbols for media communication.

When observing a certain weather phenomenon, meteorological observers should record the corresponding symbols in the "Weather Phenomenon" column of the observation record book of the day, except for a few phenomena, and also record the starting and ending time. Based on these symbols, combined with the intensity, coexistence and some characteristics of weather phenomena, a group of symbols that can be filled in weather maps are called cartographic symbols.

Weather process is the process of weather phenomena changing with time in a certain area. All kinds of weather systems have certain time and space scales, and they are intertwined and influence each other.

The combination of many weather systems constitutes a large-scale weather situation and hemispheric and even global atmospheric circulation. The weather system is always in the process of rebirth, development and extinction, and there are corresponding weather phenomena in different development stages.

Extended data:

Clear: it means that there are no clouds or scattered clouds in the sky, but the cloud amount is less than110, which is called clear. Sometimes there are very high and thin clouds in the sky, but they have little effect on sunlight.

Cloudy: it can be cloudy when the amount of low clouds in the sky accounts for 4/ 10 ~ 7/ 10 of the sky area or the amount of high clouds accounts for more than 6/ 10 of the sky area.

Cloudy day: it is called cloudy when the amount of clouds in the middle and low clouds accounts for more than 8/ 10 of the sky area. Cloudy days are dark days, and little or no sunlight can penetrate the clouds.

Fog: refers to a large number of water droplets or ice crystal particles suspended in the air near the ground. When this aggregate reduces the horizontal visual distance below 1000 meters, it is called fog; When the visible distance drops to 1000 ~ 10000 meters, it is called light fog.

Light rain: it is called light rain when the rainfall in 4 hours is less than 10.0mm or 1 hour is less than 2.5 mm. ..

Moderate rain: the rainfall within 24 hours is 1 0.0 ~ 24.9mm or the rainfall within1hour is 2.5 ~ 8.0mm..

Rainstorm: Rainstorm is called when the rainfall in 24 hours is less than 25.0 ~ 49.9mm or 1 hour reaches 8.1~15.9mm..

Rainstorm: Rainstorm is called when the rainfall reaches or exceeds 50.0mm in 24 hours and 1 hour reaches or exceeds16.0mm.. Heavy rain occurs when the rainfall reaches 100.0 ~ 199.9 mm; The rainfall of 200.0 mm is called rainstorm;

Thundershower: refers to sudden rainfall accompanied by thunder and lightning, which is characterized by short rainfall time, sudden start and end, and great changes in precipitation intensity. Intermittent precipitation accompanied by lightning and thunder.

Hail: It is a kind of solid precipitation. Refers to spherical or conical ice cubes with a diameter of 5.0 mm, and it will rain heavily in the clouds. The shape is also irregular. The monomer is called hail block, which consists of transparent and opaque layers. The diameter of large hailstones can reach 19 cm.

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: refers to the precipitation phenomenon that raindrops and wet snow fall to the ground at the same time. When it happens, the near-surface temperature is slightly higher than 0℃. When snow falls into this layer of air, part of it melts into water droplets.

Light snow: refers to the snow whose horizontal visibility exceeds 1000m when it snows, or whose snowfall is less than 2.5mm within 24 hours.

Medium snow: refers to the snowfall with horizontal visibility exceeding 500 ~ 1000 meters or snowfall less than 2.5 ~ 5.0 mm within 24 hours. ..

References:

Baidu encyclopedia-weather symbols