Weather Hazards Flashcards
Global Atmospheric Circulation
- Air that is sinking towards the ground surface forms areas of high pressure (for example, at the North Pole). Winds on the ground move outwards from these areas.
- Air that is rising from the ground surface forms areas of low pressure on the ground, for example at the Equator. Winds on the ground move towards these areas of low pressure.
- Winds on the ground are distorted by the Earth’s rotation. They curve as they move from areas of high pressure to areas of low pressure.
- Surface winds are very important in transferring heat and moisture from one place to another.
- The patterns of pressure belts and winds are affected by seasonal changes.
- The tilt and rotation of the Earth causes relative changes in the position of the overhead Sun. These seasonal changes cause pressure belts and winds to move north during our summer and then south during our winter
factors that let tropical storms develop?
- Between 5 and 30 degrees north and south of the equator when:
- Sea temp is 27 degrees +
- Wind shear (difference in wind speed) between higher and lower parts of the atmosphere is low
How do tropical storms develop?
- When warm surface water evaporates, rises and condenses into clouds. Releases lots of energy, producing storms. The rising air creates an area of low pressure, increases surface winds. Low wind shear prevents clouds breaking up as they rise.
- Easterly winds near the equator move storms to the west.
- They spin because of the Coriolis Effect.
- As the storm moves, the energy from the warm water strengthens the storm, wind speeds increase.
- Northern hemisphere from August to October and Southern Hemisphere from December to April
Structure of a tropical storm
- Circular, hundreds of km wide, last 7-14 days. Spin anticlockwise in north and clockwise in the south.
Features of a tropical storm
- The centre > the eye. 50km across, caused by descending air. Low pressure, high temp, no rain.
- Eyeball surrounds the eye, spiralling rising air, 160km winds, storm clouds, rain, low temp.
- Wind speed falls towards the edges, smaller clouds, less intense rain, increase in temp.
Typhoon Haiyan Summary -
8th Nov 2013. Tacloban, Cebu affected. 280mm of rain and winds reaching 314 km/h. Storm surge > waves up to 2.3m with high tide meant 5m high waves.
Primary effects of Typhoon Haiyan
- 8000 killed.
- 1 million homes were destroyed or damaged.
- 1.9 million homeless.
- Electricity lines, water supplies were contaminated with salt water.
- Floods of 600,000 hectares of farmland.
- 13 million dollars damage.
Secondary effects of Typhoon Haiyan
- Flooding > triggered landslides, blocked roads and delayed aid.
- 5.6 million lost their jobs.
- Lack of clean water caused disease like dysentery.
Immediate response to typhoon Haiyan
- Warnings broadcast 2 days before. 800000 could evacuate.
- Fisher men didn’t go to sea.
- State of emergency, charities offered aid
- Pit latrines for 100000 to help prevent disease
LT responses to typhoon Haiyan
- UN appealed for 300 million dollars to help fund rebuilding and relief.
- Storm-resistant houses built by charities.
- Tourism board encouraged people to visit, helped fund the rebuilding process
Climate change effect on tropical storms
Makes them more frequent, intense, and more distributed
Reduce the effects of tropical storms - predictions and monitoring
Prediction and monitoring - using radar, satellites, aircraft. Computer models used to predict path. Gives people time to evacuate e.g authorities decided which areas needed to be evacuated for typhoon Haiyan.
Planning
- Future developments can avoid high-risk zones.
- Governments plant evacuation routes.
- Emergency services can practise rescuing people from flooded areas. E.g after typhoon h, volunteers started rescue simulations to prepare for next time
Protection
- Buildings designed to withstand.
- Put on stilts.
- Flood defences can be built along rivers and coasts. E.g mangrove forests in Philippines > natural defence.
Hazards that the UK experiences
Strong winds, heavy rainfall, snow and ice, drought, thunderstorms, heat waves.