Anticyclone/Area of high pressure
When the atmospheric pressure over a region is higher than its surrounding, it is called an anticyclone or an area of high pressure. The air mass surrounding an anticyclone will move clockwise in the northern hemisphere. The weather under an area of high pressure is generally stable and fine.
Bright
The sky is covered by a large amount of thin cloud with sunshine occasionally.
Cloudy
The sky is covered with a total cloud amount of between six eighths and eight eighths.
Depression / Cyclone / Area of low pressure
When the atmospheric pressure over a region is lower than its surrounding, the system is called a depression or cyclone. The area of a depression has no definite size and its diameter can range from 100 km to 2 000 km. The weather under an area of low pressure is generally unstable. The air mass surrounding a depression will move counterclockwise in the northern hemisphere, and clockwise in the southern hemisphere.
Anticyclone / Area of high pressure
When the atmospheric pressure over a region is higher than its surrounding, it is called an anticyclone or an area of high pressure. The air mass surrounding an anticyclone will move clockwise in the northern hemisphere. The weather under an area of high pressure is generally stable and fine.
Bright
The sky is covered by a large amount of thin cloud with sunshine occasionally.
Cloudy
The sky is covered with a total cloud amount of between six eighths and eight eighths.
Cold front
The boundary line between an advancing cold air mass and a warm air mass. During the passage of a cold front, the local weather changes as follows : pressure increasing, temperature falling, wind veering (clockwise change in direction), accompanied by showers and thunderstorms. Generally, the cold fronts in southern China is not strong and may not bring so remarkable weather changes as mentioned above.
Depression / Cyclone /
Area of low pressure
When the atmospheric pressure over a region is lower than its surrounding, the system is called a depression or cyclone. The area of a depression has no definite size and its diameter can range from 100 km to 2 000 km. The weather under an area of low pressure is generally unstable. The air mass surrounding a depression will move counterclockwise in the northern hemisphere, and clockwise in the southern hemisphere.
Dew
Radiation cooling at night causes the air temperature to drop. When the air temperature falls below the dew-point, which is the temperature that the air becomes saturated with moisture, some water vapour condenses from saturated air near the ground to form dew. Dew usually appears in the early morning and condenses on grass or other ground objects.
Drizzle
Precipitation of water drops of very small size.
Fine
The sky is covered by a total cloud amount of less than six eighths. However, it can still be described as fine even though the total cloud amount is greater than six eighths if the cloud layer is thin enough to let plenty of sunshine to penetrate.
Fog, Foggy, Mist,
Misty, Haze, Hazy
Fog is the suspension of small particles formed by the condensation of water vapour in the air near the ground surface, reducing the visibility to less than 1 000 m; it is called mist if the reduced visibility is equal to or above 1 000 m; it is called haze if the visibility is reduced due to small dust or smoke particles.
Rain
Precipitation of water drops from deep and thick cloud layers. It is more persistent than showers but the rainfall amount is less.
Showers
Brief precipitation usually from convective clouds. It is characterized by the sudden start and end of the precipitation as well as the fine weather before and after its occurrence.
Sunny
Plenty of sunshine for most time of the day.