Weather Hazards (from 4th form revision booklet)

what factors affect a place’s climate? (4 bullet points)

• latitude

• relief

• distance from sea

• the global circulation

define global atmospheric circulation

large-scale, 3 cell movement of air across planet + helps explain location of world climate zones + distribution of weather hazards

where do tropical storms occur?

between 5 and 30 degrees north + south of Equator

name 3 conditions which cause tropical storms

• low latitudes (5-30 degrees n + s of equator)

• ocean temps above 27°C at depth of 60-70m

• low wind shear

how does low latitudes contribute to the formation of tropical storms?

• temps higher here than at poles so sea + air heated quickly to higher temps

• air pressure = low + air rises

• Coriolis effect strong enough for tropical storms to spin

how does ocean temperature contribute to the formation of tropical storms?

provides heat + moisture so warm air rises rapidly

how does low wind shear contribute to the formation of tropical storms?

wind = constant + doesn’t vary with height so clouds rise to high altitudes without being torn apart

what are the 9 steps to the formation of tropical storms?

1. air heated above surface of warm tropical oceans

2. warm air rises rapidly under low-pressure conditions

3. strong winds form as rising air draws up more air + moisture

4. rising air spins around central eye of storm bc Coriolis effect

5. rising air cools + condenses large cumulonimbus clouds + torrential rainfall

6. heat given off as it cools, powering tropical storm

7. cold air sinks in eye so = clear + dry + calmer

8. tropical storm travels across ocean with prevailing wind

9. when meet land, loses source of heat + moisture so loses power → storms track north in northern hemisphere + south in southern hemisphere

how does climate change impact the distributions of tropical storms?

location of storms expected not to change significantly

how does climate change impact the frequency of tropical storms?

• expected to stay same or decrease

• category 4-5 storms expected to increase

• category 1-3 storms expected to decrease

how does climate change impact the intensity of tropical storms?

• since 1970s, number of severe category 4+5 storms increased

• every 1°C in sea surface temps = 3-5% increase in wind speed

• warmer atmosphere = heavier rainfall + flooding

describe pressure belts

• at equator strong heating causes air to rise → low pressure = form cloud + rain

• air sinks at 30°N/S → high pressure = form dry + clear weather (Hadley cell)

• at poles, cold denser air sinks → high pressure + flows towards equator

• at 60°, air rises again → low pressure (Polar cell)

• Ferrel cell lie btw Hadley + Polar cells

describe surface winds

• winds move from high to low pressure

• deflected by Coriolis effect due to earth’s rotation

• right in northern hemisphere

• left in southern hemisphere

how does monitoring reduce the effects of tropical storms? (2 bullet points)

• satellites monitor cloud patterns associated with tropical storms

• The Global Precipitation Measurement satellite monitors high altitude rainclouds every 3 hours which indicate whether tropical storm will intensify within 24 hours

how does prediction reduce the effects of tropical storms? (2 bullet points)

• supercomputers give 5 days warning + predict location within 400km

• track forecast cones plot the tropical storm’s predicted path (approx 70% occur within cone)

how does planning reduce the effects of tropical storms? (3 bullet points)

• people who live in tropical prone areas make plans + prepare what they need to deal with the effects

• prepare disaster supply kits

• know where evacuation shelters are

how does protection reduce the effects of tropical storms? (4 bullet points)

• develop coastal flood defences

• reinforce buildings

• place valuable stuff in waterproof container on top floor

• cover window/door with hurricane shutters