Hazardous environments atmospheric hazards Flashcards
Explain the formation of tropical cyclones.
Pre-Conditions for tropical cyclones.
Sea temperatures must be over 27oC to a depth of 60 metres for an extended period as the warm water gives large quantities of heat when it is condenses, the driving force begin the tropical storm.
The low pressure area has to be far enough away from the equator so that Coriolis force creates rotation in the rising air mass - if it is too close to the equator there is insufficient rotation and tropical storms will not develop.
Conditions must be unstable - some tropical lower pressure systems develop into tropical storms.
Pre-existing winds (those not created by the storm) should be coming from the same direction and at close to the same speed to avoid ripping the storm apart.
Impacts of tropical storm
Tropical storm bring intense rainfall and very strong winds, which may in turn cause storm surges and coastal flooding, and other hazards such as landlsides.
Tropical storm are characterised by enormous quantities of water. This is due to their origin over tropical. High-intensity rainfall, as as large totals - up to 500mm in 25 hours invariably cause flooding in especially low lying areas.
Their path is erratic, so it is not always possible to give more than 12 hours notice of their position. This is insufficient for effective evacuation measures.
How are tropical storms measured?
Tropical storms are the most violent, damaging and frequent hazard affect the tropical regions. They are measured on the Saffir-Simpson Scale, which is a 1-5 rating based on the tropical storm’s intensity. It is used to give and estimate of the potential property damage and flooding expected along the coast from a tropical storm landfall.
Wind speed is the determining factor in the scale, as storm surge values are highly dependent on the slope of the continental shelf and the shape of the coastline in landfall region. Tropical storms can also cause considerable loss of life.
