hazardous environments - tropical cyclones Flashcards
what is a hazard?
a hazard is an event that threatens, or actually causes damage and destruction to people, their property and settlement.
why are some places more hazardous than others?
- some places experience natural hazards more frequently
- some places can cope better with the damaging impacts
- some places have stronger and more destructive hazards
hazards can be classified into 4 main categories. they can be natural or man-made.
what are the 4 main categories?
- geology
- climate
- biological
- technological / human
TROPICAL CYCLONES:
what constant wind speed does the tropical storm need to reach to be classified a tropical cyclone / typhoon / hurricane.
119 km/h
what is the source region?
where the tropical cyclone starts the development
what is the track?
the path that the TC follows
what are tropical cyclones?
large, rotating that form over oceans in tropical areas.
they are devastating when they reach land.
characteristics of tropical cyclones:
- water temp has to be over 27C° to be able to form
- form near the end of summer and in autumn
- mostly occur in the north pacific
- normally move from E to W
- the eye wall has the fastest winds
- areas of very low air pressure
how are tropical cyclones formed?
hot, moist air rises.
big clouds form.
low pressure is created at sea level.
air from high pressure rushes to replace it, not in a straight line but in swirls. (due to Coriolis effect) caused by the earths rotation.
consequences of a tropical cyclone?
one the cyclone has been formed, cold air at the top of the storm sinks down a funnel where it is then heated, and pulled into the spinning circle. the entire cyclone drifts sideways because of the winds. the cyclone is so powerful that it depresses the sea beneath it (pushes down) creating a storm surge as the water is pushed away and it needs to go somewhere.
can hurricanes be formed near the equator?
no, because they have to spin, and the Coriolis effect only occurs away from the equator.
where do hurricanes / tropical cyclones get their energy from?
they get it from heat in the water, so the longer it travels in the sea the stronger and bigger it will get. once it reaches land it creates a lot of damage but loses its energy on the way and eventually dies out.
where are these hurricanes / tropical cyclones usually located?
between the tropics ( of cancer and Capricorn)
what does a tropical cyclone need to be able to develop?
- a warm sea
- air must be humid and warm
- anti-clockwise movement of air.
- wind shear
what is wind shear?
wind shear is the small changes in wind and speed direction with increasing altitude.
