Transcript Weather of HK

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 160C
Wind from south-east
2.5 m/s
Tropical cyclone/typhoon
A very low pressure system
Characteristics
Pressure at centre below 1000 hPa
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 22o20’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