What is the acronym for the British climate and what does it stand for
CTWM (cool summers temperate winters western (of a continent) maritime island and so it is wet)
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Describe the British climate
It is a climate without extreme temperature, with rainfall throughout the year. It is unpredictable due to air masses and heavily influenced by low pressure systems (depressions)
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What is the temperature of the british isles like?
colder than other countries at a similar latitude in summer. Average summer temperature is 18C and average winter temperature is between 2 and 7C
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What is the precipitation of the british isles like?
Rainfall varies spatially with the highest totals on the west coast (2500mm) compared to the east coast, also known as the lowlands (500mm). Summer and winter are the driest seasons. Most rainfall is brought by fronts.
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What is the wind of the british isles like?
The prevailing wind is from the southwest bringing low pressure systems and causing strong gales in autumn and winter.
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what is the longitudinal range of the british isles?
29-60N
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What are the 5 air masses that dominate the British isles
Brings cool conditions, originating over north american and asian land masses. As it travels over the Atlantic it is slightly warmed by the relativ eheat resulting in rising air, blustery showers, cumuliform clouds and depressions.
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what percentage of our weather is accounted for by the polar maritime air mass?
25%
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Describe the tropical maritime air mass
Approaches from the south-west from the sub-tropical atlantic. it cools as it travels across the ocean and becomes more stable, bringing humid, damp, overcast weather. Can bring sea fog to areas such as dartmoor and western ireland.
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Describe the arctic air mass
Similar to polar maritime, although due to a shorter exposure to the sea the air is colder and less moist. can bring snow, most commonly to scotland.
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what percentage of our weather is accounted for by the arctic air mass?
2%
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Describe the Polar continental air mass
Brings very cold weather, lower than -10C at night, although only affects the british isles from november to april
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Describe the tropical continental air mass
Tropical continental is most common during the summer months, and can bring dry heat waves of over 30C during the day. It originates in the sahara, so can carry sand particulates affecting visibility.
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What is a depression
A relatively low pressure system where surface winds rotate in an anticlockwise direction. They bring cloudy, rainy, windy weather.
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where do depressions that affect the uk begin?
usually in the atlantic, moving eastwards towards the UK
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What is stage 1 of the formation of a depression?
Warm tropical air from the south meets cold polar air from the north. Warm air is forced to rise as it is less dense, creating low pressure.
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What is stage 2 of the formation of a depression?
Cold air pushes south into warm, warm air pushes NE into cold air. Begins to rotate anti-clockwise. Moderate showers will hit first as warm air gradually creeps over the cold, creating nimbostratus. cumulonimbus follow as cold air forces warm air up
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What is stage 3 of the formation of a depression?
The cold front catches the warm front , forcing the warm air to move up into the atmosphere. the two cold fronts merge to form an occluded front and then just one large cold air mass.
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What is an anticyclone?
A relatively high pressure system where surface winds rotate in a clockwise direction. they are high pressure but as they are so large they have a low pressure gradient, creating gentle winds.
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How big are anticyclones?
they can be 1000km in diameter
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describe Summer anticyclones
Dry, clear, hot sunny days with very little wind. Those that affect the UK are often sourced in north africa and brought by the tropical continental air mass. There is a chance of thunderstorms especially if the high pressure is tropical maritime.
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Why are thunderstorms dangerous
they can bring heavy rainfall in a short period of time which can cause flash flooding.
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What are the dangers of summer anticyclones
it is very hot and sunny due to lack of clouds=sunburn/heat stroke. Lack of rainfall can cause problems for farmers or lead to water shortages as anticyclones can last for days (known as a heatwave)
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What happens at night in summer anticyclones?
due to a lack of clouds, the ground will cool rapidly at night, allowing early morning mist and dew to form.
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Describe winter anticyclones
Conditions are dry, clear, and sunny but very cold. Winter anticyclones that affect the UK are often sourced in Central Asia or Siberia, and are brought by the Polar Continental Air mass. cold because of reduced insolation in winter+lack of clouds
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What happens to water vapour in winter anticyclones and why is this hazardous?
Any water vapour in the air condenses onto the ground as dew or frost, or in the air as fog. This can make travelling hazardous and can disrupt farming (especially fruit farming)
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Case study for British storm?
Storm Desmond 2015 5th-6th december
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Other cards in this set
Card 2
Front
Describe the British climate
Back
It is a climate without extreme temperature, with rainfall throughout the year. It is unpredictable due to air masses and heavily influenced by low pressure systems (depressions)
Card 3
Front
What is the temperature of the british isles like?
Back
Card 4
Front
What is the precipitation of the british isles like?
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