Weather Hazards

• Sun warms the Earth at the equator,causing the air to rise,creating a low pressure belt
• As air rises it cools and moves away from the equator
• 30 degrees north and south of the equator,the cool air sinks, creating a high pressure belt
• At the ground surface,the cool air moves either back to the equator (as trade winds) or to the poles (westerlies), These winds curve because of the earth's rotation - the coriolis effect
• 60 degrees north and south of the equator the warmer surface winds meet colder air from the poles,warmer air rises creating low pressure
• some air moves back towards the equator and the rest moves towards the poles
• At the poles the cool air sinks,creating high pressure,which is then drawn back down to the equator
• Tropical Storms develop between 5° and 30° north and south of the equator
• for tropical storms:

  Sea temp 27°C or higher

  wind shear(difference in wind speed) between higher and lower parts of the atmosphere is low
• Centre of the storm is called the eye - up to 50km across and is caused by descending air. Low pressure,light winds,no clouds,and high temp
• the eye is surrounded by the eyewall where there's spiralling rising air,very strong winds (160km/hr) storm clouds, torrential rain,and a low temp