Page 173 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

Chapter 5 global Temperatures 137
0 250
500 KILOMETRES
INDIAN OCEAN
Australian Victoria Capital
Territory
Tasmania
Western Australia
Northern Territory
South Australia
Queensland
New South Wales
▲Figure 5.1.2 Record-setting heat wave in Australia, 2013. Map shows land-surface temperature differences recorded from satellite data in early January. above-average values (positive anomalies) are shown by red colours; below-average values (negative anomalies) are shown by blue colours. The baseline temperatures for comparison are from the same week during 2005–2012. [Data from Aqua MODiS, naSa.]
and an overall estimated economic cost of US$15 billion.
The record-breaking australian heat wave of January 2013 lasted not days but weeks, with temperatures regularly exceeding 45°C at several locations across the country. according to the australian Bureau of Meteorology,
the heat wave registered the highest average temperature ever recorded across the country (40.3°C) during the hottest two-day period (January 7–8) in australia’s history. Figure 5.1.2 shows the pattern of above-average land-surface temperatures across the continent during this time. in mid- January, weather forecasters added two new colours to their heat maps
to extend the range of temperatures beyond 50°C to 54°C. This heat
wave continued a trend of four consecutive months of record-breaking temperatures in australia.
although heat waves in australia are nothing new, the extent of heat across the country and the persistence of the heat wave over time represent new con- ditions and suggest a continuing trend of temperature increase for the country. according to the chairperson of the international Panel on Climate Change (iPCC), this heat wave, and others, re- lates to recent trends of global climate change.
PACIFIC OCEAN
LAND-SURFACE TEMPERATURE ANOMALIES (C°)
≤-15 0 ≥15
sufficient to keep body temperature within the proper range. It is the combination of high air temperatures, high humidity, and low winds that produces the most heat dis- comfort for humans. This is why the effects of heat are more pronounced in the hot, humid southeastern United States than in the dry environments of Arizona; although temperatures in deserts may be more extreme, the risk of heat-related illness, or heat stress, is higher in humid environments.
Heat stress in humans takes such forms as heat cramps, heat exhaustion, and heat stroke, which is a life-threatening condition. A person with heat stroke has overheated to the point where the body is unable to cool itself—at this point, internal temperature may have
risen to as high as 41°C, and the sweating mechanism has ceased to function.
During appropriate months, using a method analo- gous to that for reporting wind chill (discussed at the beginning of the chapter), the NWS reports the heat index in its daily weather summaries to indicate how the air feels to an average person—its apparent temperature— and gauge the human body’s probable reaction to the com- bined effects of air temperature and humidity (Figure 5.18). Canada uses the humidex, based on a similar formula. For more information and forecasts in the United States, see www.nws.noaa.gov/om/heat/index.shtml; in Canada, go to “heat and humidity” at www.ec.gc.ca/meteo-weather/default.asp? lang=En&n=6C5D4990-1.
Georeport 5.4 Record-Breaking Heat Hits China in 2013
Temperatures soared across asia in July and august, 2013, setting records and causing heat-related fatalities. in Shanghai, China, with a population of over 23 million, a 3-week heat wave—including a new high temperature of 40.8°C recorded on august 7—prompted officials to issue the country’s first ever weather warning for heat and caused at least 40 reported deaths,
although the actual fatalities may be much higher. See earthobservatory.nasa.gov/iOTD/view.php?id=81870 for maps, images, and more on this heat wave.