According to the amount of clouds, the weather can be divided into

The weather can be divided into sunny, cloudy and cloudy days.

Cloudiness refers to the number of clouds covering the horizon of the sky. The location of the estimated cloud cover must be able to see the whole sky. When the sky is partially blocked by obstacles such as mountains and houses, the cloud cover should be estimated from the uncovered part of the sky. If a part of the sky is covered by precipitation, this part of the sky should be regarded as covered by clouds that produce precipitation.

Cloud amount observation includes total cloud amount and low cloud amount. The total cloud amount refers to the total cloud amount covering the sky during observation, and the low cloud amount refers to the cloud amount covering the sky, both of which are integers. Estimate the position of cloud cover and see the whole sky as much as possible. When a part of the sky is blocked by obstacles (such as mountains and houses), the cloud cover should be estimated from the unobstructed sky. If a part of the sky is covered by precipitation, this part of the sky should be covered by clouds that produce precipitation.

Extended data

In recent 30 years (1979 -2009), the global average total cloud cover is about 59%. The global total cloud cover has obvious zonal distribution characteristics: there are very obvious high cloud coverage areas in both the northern hemisphere and the southern hemisphere, and the cloud cover is basically higher than 80%, showing a zonal distribution. Among them, the high cloud coverage area in the northern hemisphere is located in the high latitude area (60 ~ 90 N) and extends to the North Pacific Ocean, the North Atlantic Ocean and the northeast of North America respectively, while the high cloud coverage area in the southern hemisphere is located in the middle latitude area (40. Secondly, the high cloud coverage area is also distributed in the mainland and Central Asia near the equator.

The low-value areas of cloud cover are relatively dispersed. There are two obvious low-value areas with cloud cover less than 30% in the equatorial Pacific, North Africa and the Middle East. In addition, there are some low-value areas in southern Africa, near Australia, south-central North America and South America, and there are two sub-low-value areas with cloud cover of 30%~40% on the ocean surface in the low latitudes of the northern hemisphere.