Chapter 9 weather studies study guide PDF

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AMS Weather Studies Chapter 9 Critical Thinking Questions

Seasonal shifts in the intertropical convergence zone (ITCZ) are greater over continents than over the .1 .ocean. Explain why a. The average location of the ITCZ occurs approximately at the latitude where Earth’s mean annual surface temperature is highest (known as the heat equator). Surface temperatures vary more over land, .causing the ITCZ to shift more over the continents than over the ocean The Gulf Stream in the western North Atlantic Ocean strongly influences weather and climate of the .2 East Coast of North America and northwest Europe. Explain which ocean circulation the jet stream is part . of and what atmospheric circulation feature drives this ocean circulation feature a. The warm Gulf Stream current is the eastern portion of the subtropical North Atlantic gyre. This gyre . rotates in a clockwise fashion and is centered at about 30°N latitude Explain why in winter a meridional flow pattern in the westerlies over the coterminous U.S. is more .3 .likely to favor development of extratropical cyclones than a zonal pattern in the westerlies a. In a meridional flow pattern, warm air moves northward and cold air moves southward causing air masses to collide. The collision of these contrasting air masses causes the warm air mass to override the cold air mass, favoring the development of extratropical cyclones. In a zonal flow pattern, cold air masses . tend to stay to the north and warm to the south allowing for the dissipation of any extratropical system ? How does a jet streak provide upper-air support for the development of an extratropical cyclone .4 a. A jet streak is an area of accelerated air flow within a jet stream and provides upper-air support for an extratropical cyclone by contributing strong horizontal divergence aloft and thus exceptionally strong . winds. Cyclone development is most prominent under the left front quadrant of a jet streak Explain why a ridge in the 500-mb flow pattern is associated with an underlying mass of relatively .5 .warm air a. An area of high contour heights at the 500-mb level indicates a ridge. Relatively warm, less dense air in the column below the 500-mb level is responsible for the high contour heights. Air pressure drops less rapidly with altitude in a column of warm air compared to vertical pressure changes in a column of cold .air

? Why is ENSO referred to as a coupled phenomenon .6 a. ENSO is referred to as a coupled phenomenon because it depends on the feedbacks between the ocean and atmosphere. Variability in the system cannot be explained exclusively as an atmospheric or .oceanic event

AMS Weather Studies

. Explain how Ekman transport produces coastal and equatorial upwelling .7 a. The Ekman transport drives warm surface waters away from the equator or coastline, causing cold, . nutrient rich waters to well up from below Scientists are continuing to improve techniques to successfully predict El Niño and La Niña episodes .8 ?months or more in advance. What are the advantages of such predictions a. More accurate predictions of El Niño and La Niña allow people to better prepare and cope with the impacts. Forecasts of El Niño and La Niña allow for strategic planning in agriculture, fisheries, and water .resource management What is the polar vortex? Explain how positive and negative phases of the Arctic Oscillation influence .9 .the polar vortex and its impact on the United States a. The polar vortex refers to the band of winds in the middle and upper troposphere blowing in a mostly zonal pattern counterclockwise around the Arctic. This upper-air low pressure system is strongly influenced by the phases of the Arctic Oscillation. During the AO positive phase, the polar vortex is strengthened and remains in the Arctic region, with zonal flow prevailing. During the AO negative phase, winds weaken, and bitterly cold Arctic air masses move out of their far northern source regions southeastward into middle latitudes. This leads to colder than usual winter weather for most of the U.S., a higher frequency of heavy lake-effect snows downwind from the Great Lakes, and an increased . likelihood of nor’easters along the U.S. Eastern Seaboard What is the Madden-Julian Oscillation (MJO)? How does the MJO convective phase influence .10 ? atmospheric rivers a. The Madden-Julian Oscillation is an area of convection that develops in the tropical Indian Ocean and migrates eastward, traversing the globe in 30–60 days. The MJO enhanced rainfall or convective phase is coupled to a suppressed rainfall phase. The MJO convective phase can further moisten the Pineapple . Express atmospheric river

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