What is a tropical storm?
Tropical storms are low pressure weather systems that develop on the tropics. They ‘fuel’ on water vapour’ and begin in areas of low pressure which heats the surface causing warm air to be drawn upwards, tend to have a lifespan of 7-14 days.
Distribution of tropical storms
- Occur between 5+20 degrees North and South of the equator
- Move west (d2 trade winds)
- Most destructive in Caribbean Sea, Arabian sea, off Madagascar etc
What is happening to the frequency and regularity of tropical storms?
Frequency- increasing (number of storms increasing)
Regularity- decreasing (storms are getting stronger, lasting longer- less regular)
Name 4 conditions needed for tropical storms to intensify?
- Temperature
- Ocean depth
- Location
- Air movement
How does temperature cause tropical storms to intensify?
- Sea temperatures above 27 degrees- heat is transferred from the ocean to the atmosphere, when water at the ocean’s surface evaporates water vapour is created causing the ocean to cool slightly, and thus heat is transferred to the atmosphere
How does ocean depth cause tropical storms to intensify?
Ocean must be at least 70km- the deeper the available warm water, the more energy there is for the hurricane
How does the location of a tropical storm cause it to intensify/occur?
- At least 5 degrees north or south of the equator-> Coriolis effect is present causing the storm to rotate, effecting the air that travels around the earth (travels at different speeds depending on location)
- The Coriolis effect will deflect air to rotate a anti-clockwise in the northern hemisphere and clockwise in the south
- Tradewinds push the hurricane to the west in the northern hemisphere
Why is movement of air needed to intensify a tropical storm?
- Movement of air needed- low level convergence of air in the lower atmospheric circulation system
- Winds have to come together near the centre of the lower pressure zone+ rapid outflow of air in the upper atmospheric circulation pushes warm air away
What weather conditions occur in the eye?
wind speeds decrease rapidly (horizontal winds remain but these are light), air is often calm, generally free of clouds
What weather conditions occur in the eyewall?
strong winds (d2 large pressure gradient), heavy rainfall, deep convective clouds rise close to earth’s surface= most dangerous and destructive part of cyclone
What weather conditions occur when a tropical storm makes landfall?
torrential rains (increased convergence of airflow and rising of moisture in the air), temperature drops (energy is being used- winds move towards low pressure, cools)
Name 4 methods used to predict storm hazards:
- Satellite and radar technology are used to track the approach of a tropical storm
- Reinforced aircraft fly through and over tropical storms
- Computer forecast models compare information on past storms and the area’s atmospheric pressure, wind and moisture
- Computer models measure low pressure, relief of land, and wind speed to calculate how much water will be pushed towards the shore by wind force
