Storm Events Flashcards
Common feature of the CTWM climate
Gales
When are gales at their worst
During the autumn, when the sea temperature is still warm enough to fuel powerful low pressure cells
Can Caribbean storms reach the UK
Sometimes during the autumn the relics of tropical storms from the Caribbean find their way across the Atlantic. However, by the time they reach the European coast much of their energy has been lost because of lower temperatures.
Where is the magnitude of gales greatest within the U.K.
The exposed western coastal areas
What are the exposed western coastal areas of the UK associated with
Low pressure weather systems and occur where there is a steep gradient - surface winds always blow from high to low pressure
How are strong winds and a steep gradient in pressure be recognised on a weather chart
Closely spaced isobars
When do severe gales occur
When the air pressure drops to a very low level.
E.g. The great storm of 1987
What was the air pressure at the centre of the low (great storm 1987)
974 mb (average is 1,103 mb)
Where are gales rare
Mid latitudes
Why are gales in the mid latitudes more damaging
The air pressure at the centre of an intense depression does not fall to such an extremely low level as it does in the tropics. Therefore, the wind speed caused by the steep pressure gradient in a tropical revolving storm is never quite matched.
What is the Beaufort scale used for
To categorise wind strength
Moderate gale
Wind speeds of between 50 and 60hm h-1
Fresh gale
Breaks twigs from trees and has wind speeds between 61 and 73 km h-1
Strong gale
Winds of between 74 and 86 km h-1
Can cause damage to buildings, particularly roofs
Whole gale
Speeds between 87 and 100 km h-1
It uproots trees and causes structural damage to buildings
