Environmental hazards
What is a 'natural hazard'?
A natural hazard is the threat of a naturally occurring event happening in a particular area often without warning, which has negative impacts on people and the landscape. Examples of natural hazards include tropical stormAn intense storm that forms in places with warm seas. Sometimes called hurricanes or typhoons., earthquakesThe sudden movement of the earth's crust., volcanoA landform created by an area in the Earth's crust through which lava, steam and ash may erupt. and tsunamiA large destructive wave caused by earthquakes, volcanic activity or landslides under water..
Globally, natural disasters kill 60,000 people per year, on average.
Tropical storms
Location
Tropical storms are found between the EquatorThe line around the centre of the Earth, parallel to the Tropics of Cancer and Capricorn. and the Tropic of CancerAn important line of latitude located at 23.5掳 north of the Equator. in the northern hemisphere and between the equator and the Tropic of CapricornAn important line of latitude located at 23.5掳 south of the Equator. in the southern hemisphere.
They originate over the eastern side of oceans and move westwards where, when they cross land, they cause great devastation before dying out. Tropical storms over 74mph are called hurricanesThe name for a tropical storm in the USA. in the USA, cyclonesThe name for a tropical storm in India . in India and typhoonThe name for a tropical storm in China. in China and Japan.
The main features of tropical storms
Causes of tropical storms
In order for a tropical storm to form, the following conditions need to be met:
- sea temperatures must be over 27掳C
- low air pressureThe weight of the air in the atmosphere.
- air spiralling upwards
- large expanse of water
- location between the tropics
- damp, moist air with humidityThe amount of water vapour in the atmosphere measured as a percentage. greater than 60% per cent