Theme 2: Changing Environments 2.3 Weather & Climate The hour-to-hour, day-to-day state of the atmosphere (temperature, precipitation, wind). Short term and localised. Climate: The average weather conditions for a place taken over at least 30 years. Long term an applied to large areas of the world e.g. The Mediterranean climate Microclimate: Localised climate conditions caused by factors such as relief and altitude e.g. Conistone in the Yorkshire Dales Physical factors How these affect the weather Human factors Altitude Temperatures decrease by 1 degree centigrade for every 100m in height High land also often receives more precipitation Reservoirs Huge damming schemes can affect the weather – increasing rainfall Aspect The direction a slope is facing In the northern hemisphere, south facing slopes are the warmest Urban areas Urban area are generally warmer (Urban microclimates) Exposure An exposed location will generally be colder than a sheltered area (Windchill) Land surfaces Water will reflect heat from the sun causing an area to warm up Buildings retain heat (urban microclimate) Vegetation will absorb solar energy causing an area to cool down

Global circulation There are 3 cells making up lobal circulation north and south of the equator. They are called Polar cell, Ferrel cell, Hadley cell At the equator air rises creating low pressure. Low pressure causes cloud and brings wet weather. Further north (e.g. where the Hadley and Ferrel cells meet) air sinks creating high pressure. This brings dry, clear weather

Two contrasting extreme weather events: 1 HIGH PRESSURE

Two contrasting extreme weather events: 2 LOW PRESSURE Primary effects of tropical storms Primary effects of tropical storms include high winds, torrential rain and storm surges at landfall (more about this one later on). There may also be localised tornadoes and waterspouts. These are all physical effects. Secondary effects of tropical storms Secondary effects of tropical storms are very wide-ranging. We tend to divide them into social, economic and environmental effects (the SEE classification). To remember this, think about how a good geographer must open their eyes and SEE the world HURRICANE KATRINA actually started off the coast of Africa many days before. The Sahara, whose land mass is almost that of the continental United States, is the largest “hot” desert in the world. The temperatures of the land mass of western North Africa grows so hot the air over this area rises to create the Africa easterly jet. A column of hot air swirls upward three miles and spreads as it races to the west coast where it dips toward the ocean. The air picks up moisture from the warm waters and continues its race westward. The flow of the ocean and the spin of the earth combined with the dry winds of the desert and the warm moist air off the Atlantic horse latitudes make this desert child grow. The storm first developed on 23 of August over south-eastern Bahamas and was upgraded and named Katrina the next day. Political: The government was criticised for its response, with many critics claiming it was very slow to respond and that the management lacked coordination. The use of emergency centres was also criticised, with the Louisiana Superdome (designed to handle 800, yet 30,000 arrived) and the New Orleans Civic Center (not designed as an evacuation center, yet 25,000 arrived) deemed by many as inadequate. Economic: Katrina damaged or destroyed 30 oil platforms and caused the closure of nine refineries World price of oil went up. Social: Racial tensions were exposed and intensified, as many of the victims were black African Americans Kanye West claiming that there was a racial reason for the slow response, given that most of the stranded people were African American. Environmental: As part of the clean-up effort, the flood waters that covered New Orleans were pumped into Lake Pontchartrain, a process that took 43 days to complete. These residual waters contained a mix of raw sewage, bacteria, heavy metals, pesticides, toxic chemicals, and oil, which sparked fears in the scientific community of massive numbers of fish dying