Atmospheric Hazards Case Studies Key terms and definitions

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Atmospheric Hazards Case Studies Key terms and definitions HOTS question: Coriolis effect The effect

Atmospheric Hazards Case Studies Key terms and definitions HOTS question: Coriolis effect The effect that Earth’s rotation has on weather patterns making storms swirl in certain directions Extreme Weather When a weather event is significantly different from normal Global atmospheric circulation The worldwide system of winds, which transports heat from tropical to polar latitudes Hazard risk The probability or chance that a natural hazard may take place High income country (HIC) A country with a GNI of $12, 746 or above Low income country (LIC) A country with a GNI of $1, 045 or below Natural hazard A natural event that threatens people or has the potential to cause damage and destruction Newly emerging economies (NEEs) A country which has begun to experience higher rates of economic development Storm surge When the sea rises as a result of wind atmospheric pressure changes Tropical storm (hurricane, cyclone or typhoon) An area of low pressure with winds moving in a spiral around a calm central point called the eye of the storm Hurricane Katrina struck North America between the 23 rd and 31 st August. It was, and still is, the costliest natural disaster in the history of the US. The Hurricane was a category 5 in the Gulf of Mexico but quickly slowed once it hit land. However the effects were still devastating. Around 2000 people were killed and the majority of New Orleans was damaged or destroyed. Hurricane Katrina is often called a ‘man-made’ disaster because the effects were made worse by human mistakes. Global atmospheric circulation is the model that explains how air moves from the equator to the poles. At certain points on earth where air rises, there is low pressure and high levels or precipitation. Where air is falling back to earth there is high pressure and conditions are usually calm. Scientists are predicting that climate change will impact the frequency and strength of tropical storms. As sea temperatures rise then storms are likely to become more powerful. If sea temperatures rise then tropical storms may occur in more areas around the world. Hurricane Catarina in 2004 was the first hurricane to strike the south-east coast of Brazil. Tropical storms have an eye in the middle, where conditions are calm. The eye wall contains the strongest winds. There are then bands of clouds moving out from the eye. Tropical storms can be up to 300 miles wide and can be up to 14 km tall. Convection currents are where warm air rises up into the atmosphere, cools and then falls back to earth. There are three large convection current cells moving from the equator north and south. Wind is formed when air moves from areas of high pressure to areas of low pressure. Due to the rotation of the Earth, the winds don’t travel in a straight line but they curve. Tropical storms are formed when sea temperatures reach at least 27°C. The warm, moist air rises into the atmosphere creating high pressure, air rushes in to balance it out creating strong winds which curve due to the Coriolis effect. Once the storm reaches land it loses its source of energy (water) so it weakens.