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UNIT 13

UNIT 13. Weather Systems.

bertha-hardy
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UNIT 13

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  1. UNIT 13 Weather Systems

  2. Figure 13.1 Full-disk image from GOES -14 weather satellite at 1:31 p.m. EST on August 17, 2009. This thermal infrared image measures radiation emission from Earth at a wavelength of 10.7 micrometers; coldest temperatures are bright white, and hottest temperatures are black. The Galapagos Islands mark the approximate location of the equator. The intertropical convergence zone appears as a discontinuous band of thunderstorms. Tropical Storm Claudette is rapidly losing energy along the eastern Gulf Coast, Tropical Depression Ana is approaching Puerto Rico, and Hurricane Bill is building in the central North Atlantic Ocean.

  3. Figure 13.2 (A) A weather map of an easterly wave in the central Pacific Ocean approaching the Marshall Islands. The trough axis is shown in bold. A second trough axis lies about 3,000 km to the east. Surface winds are shown using standard weather map symbols and show cyclonic (counterclockwise) rotation across the trough axis. Column totals of water vapor content as a proportion of atmospheric mass (parts per thousand) are plotted as dashed lines and show convergence of water vapor east of the trough axis and divergence west of the axis. (B) Cross-section along the dotted line showing the average vertical heights of cumulus clouds. Isolines of relative humidity (%) are shown, as is the percentage of cumulus cloud cover.

  4. Figure 13.3 The eye of Hurricane Mitch is still over water, but this 1998 storm is poised to strike Central America and will become the costliest natural disaster in the modern history of the Western Hemisphere. Honduras will be hit hardest, with nearly 10,000 deaths and the loss of more than 150,000 homes, 34,000 km (921,000 mi) of roads, and 335 bridges. When it is over, nearly one-quarter of the country’s 6.4 million people will be homeless, and most of the agricultural economy will be ruined. Honduras and adjacent areas of neighboring Nicaragua will carry Mitch’s scars for generations to come.

  5. Figure 13.4 Cross-sectional view of a hurricane showing its mechanics and component parts.

  6. Figure 13.5 Storm tracks of weak and severe tropical cyclones for the 150 years preceding 2006. Weaker systems, shown in blue and yellow, occur along the equator during their early stages of development and over land and in the middle latitudes as they lose energy and weaken. The steering of these systems by the easterly trade winds within the tropics and the westerlies as they move into the middle latitudes is apparent. Category 4 and 5 hurricanes are most common in the western North Pacific Ocean.

  7. Figure 13.6 Some of the worst devastation caused by Hurricane Andrew in the suburbs south of Miami on August 24, 1992. This is part of Cutler Ridge, located just inland from where the eye wall passed over the Florida coast.

  8. Figure 13.7 Seen in its post-tropical state at landfall, superstorm Sandy was much larger than a hurricane (A). Sea water pushed ashore by the • storm cascades into the construction site for the Ground Zero Memorial, Manhattan, New York (B).

  9. Figure 13.8 A 500-mb map for North America on a typical November day. The lines show the height of the 500-mb level in meters above the surface. The position of the ridge axes is shown in red; trough axes are shown in blue.

  10. Figure 13.9 Relationship between the polar jet stream and surface pressure patterns. (A) Position of the jet stream 9,000 m (30,000 ft) above North America. (B) Associated air movement around points X and Y in vertical cross-section. (C) Resulting surface pressure conditions.

  11. Figure 13.10 (a) Mature stage of a midlatitude cyclone over the southeastern United States. (A) Pressure fields, windflows, and fronts. • (B) Cross-sectional view along the dashed line mapped in (A). The vertical scale is greatly exaggerated. Cold fronts typically rise only 1 m for every • 70 m horizontal extent; for warm fronts, the ratio is about 1:200. (C) Summary of surface weather conditions along the cross-sectional transect.

  12. Figure 13.11 (A) February 2, 2011, GOES -13 satellite image of a massive winter midlatitude cyclone moving across the eastern United States. The cyclone is about 2,000 km (1,240 mi) in diameter; a large comma cloud extends from the Midwest to New England. A dry slot formed by the dry conveyor belt is faintly evident to the west of the cold front. (B) An oblique view of a midlatitude cyclone showing the relative positions of the warm conveyor belt, the cold conveyor belt, and the dry conveyor belt.

  13. Figure 13.12 Warming an air column causes it to expand vertically, raising the center of mass (which for these columns occurs at the 500-mb level). Inflation by warming is greatly exaggerated in the figure.

  14. Figure 13.13 Schematic diagram depicting accumulation of potential energy in a convective thunderstorm (A) and over a large expanse in the middle latitudes (B). The sloping motions in (B) occur at different longitudes and are not stacked above each other as this cross-section unavoidably implies.

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