Climate of Hong Kong The weather chart symbols

Climate of Hong Kong

The weather chart symbols

Anticyclone Area of high pressure Characteristics: Isobars are circular Pressure is highest at the centre and decreases away from it Winds are weak Air sinks at the centre and winds has a clockwise direction

Weather conditions Occurs in winter Skies are clear and air is dry It is cool at night and warm during the day Light winds from the northeast Weather is calm and fine

Ridge of high pressure A tongue-shaped area of high pressure Extend from a high pressure centre Characteristics: Occurs in winter and early spring Looks like a tongue Winds blows outwards from a ridge

Weather condition Fig. 21. 4 Weather is fine and calm The temperature was 160 C Wind from south-east 2. 5 m/s

Tropical cyclone/typhoon A very low pressure system Characteristics Pressure at centre below 1000 h. Pa Isobars are circular and closely spaced Winds blow anticlockwise and inwards (northern hemisphere) Heavy downpour and thunderstorm

Overcast skies and cumulonimbus clouds Eye is characterised by sinking air and fine weather Dies when it moves inland When warm moist air is cut off Mountain barriers increase the friction of movement

Weather of approaching typhoon Weather is fine Some high clouds Temperature and humidity are high Winds are light or calm Pressure falls

Front vortex arrived in HK Weather is getting worse Rainfall increases with heavy downpours Air pressure drops rapidly Wind from NE, NW to E. Wind speed is high Relative humidity is high

Eye over HK A period of fine weather No rain and few clouds Wind is light or calm Air pressure is the lowest

Eye moves away Weather is bad Wind direction is reversed and changed to southwest Wind is strong Rainfall increases Air pressure rises rapidly

Typhoon has passed: Weather is better Sky no longer overcast Rainfall gradually stops Temperature and pressure rises to normal again

Trough of low pressure A tongue-shaped area of LP Extending out from a low pressure centre Characteristics Narrow zone of low pressure Wind blows to the axis of trough

Weather conditions Occurs in late spring and early summer The pressure falls Temperature and relative humidity rise Rising of air in the trough Unsettled weather with heavy rain

Cold front A front is a surface between two different air masses. The cold air is advancing when it meets warm air

Characteristics Cold air moved beneath the warm air Warm air is forced to rise Bad weather is resulted Develop in winter and early spring when the cold air flow outward from an anticyclone

Before cold front arrives at HK Weather is relatively warm Fine weather and little cloud cover Calm or light winds blowing onshore Relatively low air pressure

Cold front arrived Temperature begins to fall Relative humidity increases Light to heavy rain falls What type of rain is formed? Describe the processes taking place along the cold front………

Cyclonic rain formed It is cyclonic / frontal rain Wind speed increases Wind direction changes from S to north Air pressure rises

Cold front has passed Under the influence of an anticyclone Temperature drops a few degrees Clear sky Relative humidity is low / air dry Off-shore winds blow from N to NE Air pressure is high Cold dry weather

Depression A depression is an area of low pressure Characteristics Develop over China in summer Gentle winds blow inward in an anticlockwise direction (N. Hemp)

Weather conditions Air is warm and wet Cloudy with showers, sometimes heavy downpours Thunderstorms Sunny periods separated by showers

Factors influencing the climate of HK

1. The Asian monsoon system Winter monsoon Temperature is low in N China Pressure is high over N China Pressure is low over the ocean/Australia Winds blow from high pressure area to low pressure area HK has offshore winds

HK is cool in winter The sky is sunny with little cloud Rainfall is little Relative humidity is low Strong NE winds

Summer monsoon Temperature is high in Asian continent Low pressure develops But high pressure develops over warmer ocean Winds blow from the ocean to the land HK has onshore winds

HK is hot in summer Most rain falls in summer with heavy downpours Light winds blow from SE to SW direction High relative humidity

2. latitude Located on the latitude 22 o 20’N

3. Nearness to the sea The sea makes the climate humid Annual temperature range moderate

4. relief Highland in HK causes relief rain in the eastern part Lower rainfall in the western part

The four seasons