weather hazards Flashcards
what explains the distribution of weather hazards
global atmospheric circulation and latitude
why are some parts of earth hotter
sun rays hit earth are concentrated on different areas depending on latitude, more concentrated at equator than poles so it is hotter
describe weather experienced under low pressure conditions
air at equator is heated and rises in low pressure, it flows to poles cools and condenses and forms rain and cloud
describe weather experienced under high pressure of equator
air sinks at 30 north and south of the equator at high pressure it brings dry clear skies known as the hadley cell
describe the weather experienced under high pressure at the poles
air is colder and denser at poles so it sinks to ground under high pressure.
air flows towards equator and warms and rises under low pressure - polar cell
what causes convention cells
low pressure belt at equator and high pressure belt at poles
what 3 cells make up convention cell
hadley cell -
polar cell
ferrel cell
what are jet streams
strong high altitude currents of air
what causes seasons
earths tilt
how do global pressure and surface winds influence precipitation (4)
rainfall high and constant all year near the equator because as hot air rises it cools and water vapour turns to rain
at the low presure zone around the equator air rises and triggers bursts of torrential rain and if they gain energy they can travel further along - this is where tropical storms form
rainfall is often higher in coastal areas in western europe because of movement of the jet stream over the jet stream. depressions or cyclones follow the jet stream bringing stormy conditions to the uks west coast
rainfall often low around tropics as dry air falls there as part of the hadley cell resulting in dry conditions
precipitation is low in polar regions and falls as snow cold air is limited and can not hold water vapour
what is the hadley cell
circulation of air between the tropics and equator results in high pressure and hot dry desert conditions
when do tropical storms (natural hazard) form
tropical warm air rises to create an area of high intense pressure
when this warm moist air rises powerful winds spiral around calm centre point creating the eye of the storm
warm air cools and condences into heavy rain and thunder storms
how are tropical storms named
depending on location
in atlantic and eastern pacific oceans – Hurricanes – Carrabean
in west of north pacifc ocean – Typhoon East Asia
Indian and South Pacific Oceans –Cyclones–South Asia
Each storm given an international name by world meterological organisation - alphabetically and alternate in gender. It makes them more recognisable and engages public
What are the conditions for a tropical storm (5)
found between 5 and 30 degrees north and south of equator
Here warm moist air rises to high altitudes
sea must be above 27 degrees and depth between 60-70m
this gives the heat and moisture causing warm air to rise rapidly in the low pressure region
latent heat is released to power the storm
Low wind so storm clouds can rise without been torn apart so usually happen in summer and autumn
why do tropical storms not occur at the equator
the coriolis effect is not strong enough for the storm to spin
what is the sequence formation of a tropical storm (10)
air is heated above the surface of tropical ocean
warm air rises quickly under low pressure
strong winds form as rising air draws in air and moisture
rising air spins around central eye
rising air cools and condenses forming large clouds of torrential rain
heat given off as it cools powers storm
cold air sinks in eye no cloud so it is clear and dry and calm
the storm travels across the ocean with prevailing winds
on meeting land it looses heat moisture and power
storm travels north in northern hemisphere and south in southern hemisphere
why do tropical storms spin
the coriolis effect bends and spins the warm rising air. Huricanes in northern hemisphere bend to the right causing clouds to swirl anticlockwise and cyclones in the southern hemisphere swirl clockwise
what direction do tropical storms travel in and why
from east to west because of the way the earth spins
what happens as the tropical storm hits land
they loose their energy source from the sea and change direction , storms in the south track south and storms in the north track north
as they pass over land friction slows them further.
what is the average life span of a tropical storm
1 - 2 weeks
what is the typical height and speed of an average tropical storm
60-70m 39mph
what is the coriolis effect
winds do not blow in straight lines as they are effected by the coriolis effect. As the earth rotates it causes wind to bend because of the earths curve and it spins faster at the equator
how will climate change effect tropical storms give 3examples
climate change will alter conditions that cause tropical storms eg atmospheric and sea surface temperatures
as temperatures increase sea levels will rise and storm surges will be higher
a warmer atmosphere means air will hold more moisture and heavy rainfall will increase so flooding will be more destructive
link between warmer oceans and intensity of tropical storms
what happens in a tropical storm (6)
strong winds, torrential rain, storm surges (rapid rise in sea level) landslides and tornadoes landslides
