Ferg_ch12_II

Ferg_ch12_II - Ch 12 Severe weather wikimedia.org Extreme...

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Unformatted text preview: Ch 12: Severe weather wikimedia.org Extreme Heat • Long or short timescales • Long timescale: – Plate movement, oceans opening and closing large regions may be cut off from moisture, into desert conditions • Short timescale: – Changes in jet stream, atmospheric convergence zones may keep moisture away for many years drought conditions • Shorter timescale: – Heat wave Drought • Drought: extended period of deficient water in a region • Reduced oceanic air masses over land (El Nino) – early Australians did not adopt agriculture • Overfarming, excessive irrigation, deforestation • Diminished crop and livestock production • Increased erosion – dust storms, desertification • Famine, malnutrition, human displacement, disease, war , wildfires ... Drought • The Dust Bowl in Canada and USA 1930-1940 • Severe drought, agriculture – no crop rotation killed erosion-preventing grasses • 2.5 million displaced in USA, 70% of rural S AB and SK require aid • blogs.ancestry.com wikimedia.org Famine • Famine: human food capacity of a region exceeded • Starvation: Food energy imbalance on the consumption side leading to death • WHO: 'hunger is the gravest single threat to the world's public health ... • ... malnutrition is by far the biggest contributor to child mortality, present in half of all cases' Famine • 70 M deaths in 20th century • 30 M 1958–61 in China • 1942–1945 Bengal • China in 1928 and 1942 • USSR 1932-33 Stalin's famine • Biafra1960s • Cambodia 1970s • Ethiopia 1983–85 • North Korea 1990s • 10 million Kenyans face starvation today Famine • Current causes: overpopulation, conflict, soil / groundwater exhaustion, drought, rising oil prices, use of biofuels, increased demand for meat in Asia. Heat Wave • Hyperthermia when human body reaches 105 o F • Deaths occurred for days after a heatwave • Heat is the biggest killer of all severe weather • USA 1992 - 2001, heat mortality: 2,190, flood mortality: 880, hurricane mortality: 150 Figure 12.10 Chicago 1995 wikimedia.org Heat Wave Europe’s Heat Wave, 2003 • Summer heat waves • Deaths – over 35,000 • Heat waves incidence expected to increase as climate warms Midlatitude Cyclones • Northern Hemisphere cyclone : counterclockwise air mass rotating around low-pressure core • Large scale: trough in jet stream juxtaposes northern cold front and southern warm front line of thunderstorms – Northeastern U.S.: low-pressure system moving up Atlantic Northeastern U....
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This note was uploaded on 03/22/2009 for the course GEOL 171 taught by Professor Tsoflias during the Spring '08 term at Kansas.

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Ferg_ch12_II - Ch 12 Severe weather wikimedia.org Extreme...

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