global hazards - tropical storms + droughts Flashcards
what are tropical storms?
they are powerful rotating storms, which are also known as hurricanes, cyclones and typhoons
- form over tropical oceans and move from EAST TO WEST during the summer and autumn steered by the trade winds
what are droughts and where do they occur?
droughts are periods when there’s much less precipitation over a specific time than is usual for the area, leading to water shortages
- drought is linked to long periods of high pressure, meaning there’s fewer clouds and less precipitation, where there are also high temperatures more water evaporates from plants lakes and streams, so more water evaporates than falls as rain
what are the causes and conditions needed for tropical storms?
- temperature of the ocean must be atleast 26.5°C, water must be atleast 60m deep
- tropical storms accur in later summer and early autumn, when the oceans are at their warmest, the moist warm air over the ocean gives the storm their energy
- tropical storms form between 5° and 15°N and S of the equator, where trade winds meet
- need to be atleast 5° from equator so the coriolis effect starts the storm spinning
- only form if the winds blow at a constant speed at ground level, allows storm clouds to rise up in a column
- because a tropical storm depends on a warm ocean for its energy, it loses energy and eventually dies when it reaches land
what is the coriolis effect?
the way the spinning of earth makes winds veer to the right in the northern hemisphere and to the left in the southern hemisphere
how are tropical storms measured?
the wind speed of tropical storms is measured using the sadie simpson scale
what other effects do tropical storms bring along?
strong winds - trees, crops, buildings, and power lines can be damaged by winds of over 102km/h
heavy rainfall - can lead to short term flash flooding, mudslides, and landslides
storm surges - low air pressure raises the level of the ocean meaning high tides can flood inland
