Climatic Hazarsa Flashcards
Definition
An extreme weather or climate event causing harm and damage to people, property infrastructure and land use, it has to be linked to atmospheric processes
Risk
The probability of loss resulting from the interaction of a hazard with a vulnerability
Low pressure systems (cyclone)
Air is rising
Fast high winds
Air moves anti-clockwise
Lots cloud and rain
Blizzards hurricane tornadoe
HUrricanes develop as?
Intense low pressure systems over tropical oceans.
Winds spiral around the calm centre: eye.
Normally develop in the westward flowing air just North of the equator known as an easterly wave
They begin as tropical depressions which are localised areas of low pressure that cause warm air to rise. These create hurricanes that persist for 24 hours which may develop into tropical storms which have great wind speeds of up to 117 kilometres./73mph.
Only about 10% tropical depressions become hurricanes
Names/location
Indian Ocean: cyclones
Pacific Ocean: typhoons
Atlantic Ocean: hurricanes
Hurricanes that affect the Caribbean and the USA mostly form in the East Atlantic and travel westwards with the easterly trade winds.
Conditions for a hurricane?
1) sea temperature must be atleast 27. Energetic evaporation from warm water carries latent heat energy in the atmosphere. When condensation occurs, this energy is released, helping to generate the very strong winds.
2) the low pressure area has to be far away enough from the equator so that the Coriolis effect creates rotation in the rising air mass. If it is too close to the Equator there is insufficient rotation and a hurricane would not develop.
They have high volume rainfall of up to 500mm in 24 hours.
Once the rising air mass has become established (a convection cell) the system is self perpetuating
The rising air releases lots of heat during condemnation. This reinforces the instability(rising of air) within hurricanes.
At the eye descends from the top of the system, as it does so it warms so can hold more moisture. Condensation is reduced and the eye remains cloudless
Hurricane hazard
Greatest on island and costal areas
Hurricane strength- the Saffir-Simpson Hurricane scale
Damage pressure(mb) Depression ---------- -------------- tropical storm ------- ------------ Category 1 minimal >980 Category 2 Moderate 965-979 Category 3. Extensive. 945-964 Category 4. Extreme 920-944 Category 5. Catastrophic <920
Wind speed kmh. Storm surge m. Depression >56 -------------- tropical storm 63-117 ------------ Category 1 119-153. 1.2-1.5 Category 2 154-177 1.8-2.4 Category 3. 178-209. 2.7-3.6 Category 4. 210-249. 3.9-5.5 Category 5 >249. >5.5
Damage from hurricanes
Category 1: damage to unanchored mobile homes, some coastal road flooding and pier damage
Type is satellite
Geostationary: orbits at a height of 35780km above the earth and takes 24 hours to complete each orbit. This means that a satellite in orbit over the Equator will appear stationary. It remains over the same spot of the earths surface.
Polar-orbiting satellites: pass over the Earth from pole to pole. The orbit is much lower and the images provide detailed info about cloud structure.
Infrared metres
Satellites carry metres that measure visible light and provide visible images.
Infrared measures temperature of cloud or earth surface. Cold surfaces usually appear white and warm ones darker
Polar front
The line which marks the meeting place of cold polar air and warm tropical air.
Jet stream
High altitude relatively strong wind concentrated in a narrow band. It causes air to rise and sink, at low pressure systems air is rising, whereas at high pressure systems air is sinking.
Air masses
They derive their temperature and humidity from the area they develop over- source regions.
Main air masses to affect UK are p polar and T tropical which meet at the polar front
Sometimes the UK is affected by E equatorial and A Arctic air masses which are divided into m maritime and c Continetial depending on humidity
Air masses which form over oceans are m moist
Over land dry - c
Frontal weather
When two different air masses converge they form a front
When a pm and tm meet they temperature difference may be 13 degrees which allows warm air to rise over cool air
LPS FORCES OPERATING
1) two air masses meet along a front
2) Coriolis force
3) the divergence of air aloft in the upper regions of the troposphere.
The combination of these is to drag air inwards to the centre of low pressure. Warmer lighter air invades the colder denser air to from the warm sector, while warm air rises over the cold air at the warm front
Where the cold air pushes the warm air up, a cold front is formed, the rising air is removed at altitude by the jet stream
Low pressure
Mid and high latitudes
Cyclone
Mixing of cold and warm air where air masses of different temperature meets
Warm air rises and forms a centre of low pressure
