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Geography - Weather Hazards - Coggle Diagram
Geography - Weather Hazards
Global Atmospheric Circulation
Air circulates between high and low pressure belts as surface winds
transfer of heat from equator to poles by movement of air
air moves due to differences in air pressure
Cells
Hadley
Ferrel
Polar
Weather around the world
equator
sun directly overhead
surface receives lots of solar radiation
hot
warm, moist air rises
forms clouds
rains
30° N & S
released most moisture as rain
dry air
few clouds and little rainfall
deserts
UK - 60° N
warm rising air
lots of cloud cover and rainfall
low pressure systems
from Atlantic by westerly winds
Tropical Storms
intense low pressure weather systems with heavy rain and strong winds
Where do they form?
between 5 and 30° N and S
sea temp is 27°C or higher
difference in wind speed between higher and lower parts of the atmosphere is low
How do they form?
1) warm surface water evaporates, rises and condenses into clouds
2) releases huge amounts of energy, producing powerful storms
3) rising air creates low pressure - increases surface winds
4) low wind shear prevents clouds breaking as they rise
5) storm stays intact
6) easterly winds near equator move storm west
7) storms spin due to Coriolis effect
8) as storm moves over ocean, energy from warm water strengthens - wind speeds inncrease
9) storms lose strength when they move over land / cooler water - energy supply cut off
When do they form?
Northern hemisphere
Aug - Oct
Southern Hemisphere
Dec - April
Features
circular in shape
100s km wide
7-14 days
anti-clockwise in N
clockwise in S
Structure
Eye
centre of storm
caused by descending air
up to 50km across
very low pressure
light winds
no rain
high temp
Eyewall
surrounds eye
spiralling rising air
very strong winds (160 km/h
storm clouds
torrential rain
low temp
Edge
wind speed falls
clouds are smaller & more scattered
less intense rain
temperature increases
Reducing the Effects of Tropical Storms
Monitoring and Prediction
radar
satellites
Global Precipitation Measurement satellite
aircraft
Global Hawk Drone
Predicitng where and when
evacuate
Planning
Future developments can avoid high-risk areas
evacuation routes
individual and community awareness
USA - National Hurricane Preparedness Week
Emergency services can prepare for disasters
Shelter box
Protection
Windows, doors and roofs with hurricane straps
withstand strong winds
Storm drains constructed in urban areas
sea walls
storm surges
stilts
storm surge
emergency generator
remove trees close to buildings
Climate Change
Frequency
Atlantic
tropical storms each decade increased
Oceans will stay at 27 C or higher for longer each year
Distribution
as average ocean temp rises
more of worlds oceans could be above 27 C
Intensity
higher sea surface temperatures
more evaporation
increased cloud formation
more energy released
more powerful storms
Atlantic
increased since 1970