What is the reason for "sunny day"

1, low-pressure trough and high-pressure ridge: on the fluctuating high-altitude westerly airflow, the trough corresponds to the low-pressure trough, warm air is active in front of the trough, rain and snow weather, cold air control behind the trough, and gale cooling weather; The peak corresponds to the ridge of high pressure and the sky is clear.

2. Cold front: Cold front is the front of cold air, which pushes cold air to warm air at the junction of cold and warm air mass. 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.

A sunny day means there is not much cloud cover. Generally speaking, it is easy to clean in high pressure area. Because the air flow in the high pressure area drops, it seldom gathers rain in the sky. Clouds in the clear sky are generally less than 30% (that is, 30%).

Extended data

Other weather reasons:

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.

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