The Challenge of Natural Hazards: Atmospheric Hazards Flashcards
Global atmospheric circulation
The movement of air around the Earth to try to balance the temperature.
Weather
Day to day conditions (e.g. rain).
Climate
Average conditions gathered over a period of time (e.g. cold winters).
Stages of global atmospheric circulation:
1) At equator sun warms earth, causing it to heat air above it making it rise. Low pressure forms clouds (rain).
2) As warm air rises it cools and sinks. This process moves air 30 degrees north and south of equator (@ tropics), creating the Hadley cell.
3) At 30 degrees north and south of equator, cool air sinking creates high pressure which causes cloudless skies and low rainfall.
4) Cool air reaches surface of Earth and move as surface winds from high pressure to low pressure - either back to equator (trade winds) or to poles (westerlies).
5) At 60 degrees north and south of equator, warmer surface winds meet colder air from poles. Warm air is less dense so it rises causing low pressure (rain). Ferrel cell.
6) At poles cool air sinks, creating high pressure (no rain). High pressure air is drawn back towards equator as surface winds. Polar cell.
Surface air
Transfers heat and moisture from one place to another.
Coriolis effect
Winds are deflected (to the right in the northern hemisphere and to the left in the southern hemisphere) due to the spinning of the Earth.
Global distribution of tropical storms
Found on either side of equator, in between the Tropic of Cancer and the Tropic of Capricorn.
Mostly found in Indian Ocean in east and travel west.
Formation of a tropical storm (hurricane):
1) Tropical ocean of at least 27 degrees heats up air above it causes the warm, moist air to rise. Low pressure.
2) As air rises it draws in more air and water vapour to cause torrential rain.
3) Trade winds and Coriolis effect causes air to start rotating.
4) Colder air above storm is denser and sinks in the calm eye. Heat is given off as it cools, powering storm.
4) Warm air condenses to form clouds, which cause precipitation.
5) Winds outside of hurricane keep it spinning and cause it to travel west, to land.
6) On meeting land it loses its source of heat and moisture, so loses power.
How has climate change affected tropical storms?
Frequency of tropical storms has not changed.
Sea heats up due to climate change, and more moist and warm air to fuel hurricanes makes them more intense.
Reasons for MORE people to be affected by a tropical storm:
Light weight building materials Coastal location Low lying land Storm path not predicted High population density High wind speed Lack of communications and warnings High storm surge
Reasons for FEWER people to be affected by a tropical storm:
Sturdy building materials Cliffs on coastline A means to move inland Cold air there, to reduce hurricane’s energy Storm path predicted Low wind speed Higher land Low population density Good communication and warnings
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Primary effects
- At least 6340 killed, most drowned by storm surge
- 5m storm surge
- 130,000 houses destroyed
- 90% of Tacloban city destroyed
- Habitats and crops destroyed
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Secondary effects
- $14 billion of damage
- Water supply polluted
- 4.2 million homeless
- Looting and violence in Tacloban
- Airports unusable for supplies
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Immediate responses
- Nearly 1,600 evacuation centres set up
- Field hospitals set up to help injured
- UK aid charities provided shelter, food and medical supplies
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Long-term responses
- UN appeal raised $300 million
- Typhoon warning systems have been improved
- People are now better educated on how to respond
Case study of a tropical storm in an LIC: Typhoon Haiyan, Philippines, 2013
Prediction/monitoring
Philippines is an LIC, so minimal investment went into prediction, planning and protection schemes.
Actual path of tropical storm was further south then predicted, so people who were evacuated to the south were in more danger.
Lack of scientific equipment and good building materials.
Prediction for an atmospheric hazard
Use of satellites to monitor wind patterns allows for paths of tropical storms to be predicted.
This can help with evacuations.
Planning for an atmospheric hazard
Avoid building in high risk areas.
Emergency drills.
Evacuation routes.
Protection for an atmospheric hazard
Reinforced buildings and stilts to make safer.
Flood defences such as levees and sea walls.
Replanting Mangroves.
Severe weather
Weather that damages property and land, and puts humans, animals and plants at risk.
Examples of severe weather events in the UK
2003 - heatwave in UK and Europe, over 2000 people may have died due to hottest European summer since 1540.
2006 - tornado in London, 6 people injured and £10 million in damage.