What does the weather forecast mean that the probability of precipitation is 70%?
There are two situations:
First, if it is rainy or snowy weather, the percentage number next to the raindrop or snowflake icon represents the probability of rainfall or snowfall. Second, if the weather is sunny or cloudy, there will be no such percentage.
This kind of weather forecast using probability has been used in the United States since 1966, Japan in 1980, and China officially started in Beijing and Shanghai in 1995.
And a more elusive word is often mentioned - precipitation probability. Weather forecasters often announce on TV that the probability of precipitation today is 70%. This precipitation probability means that the probability of rain in a certain area is 70%.
Extended information
Commonly used terms in weather forecast:
Sunny: The sky has less than 30% cloud cover.
Overcast: The sky has cloud cover accounting for 90% or more.
Fog: A large number of tiny water droplets or ice crystals floating in the air near the ground, reducing horizontal visibility to less than 1 km, affecting transportation.
Light rain: daily precipitation is less than 10 mm.
Heavy rain: daily precipitation is 25.0-49.9 mm.
Thunderstorm: intermittent precipitation that falls and stops accompanied by lightning and thunder.
Hail: With the intense vertical movement in cumulonimbus clouds, small hail nuclei repeatedly rise, condense, fall and melt, growing into small ice cubes with alternating transparent layers and falling, which has an impact on crops.
Freezing rain: Raindrops freeze on the ground on the surface of objects below 0℃, also known as rain (frozen by fog droplets, called rime). They often fall down and break power lines, causing the road to freeze and affecting Communications, power supply, transportation, etc.
Sleet: The temperature near the ground is slightly higher than 0℃, wet snow or rain and snow fall at the same time.
Light snow: The daily snowfall (melted into water) is less than 2.5 mm.
Moderate snow: Daily snowfall (melted into water) 2.6-4.9 mm.
Baidu Encyclopedia—Weather Forecast