UNIT 7—LESSON 5
SOUTHERN HEMISPHERE ANALYSIS
OVERVIEW Identify the differences between Northern Hemisphere and Southern Hemisphere analysisprocedures.
Mean pressure characteristics
Major frontal zones
Synoptic characteristics of the pressure pattern
Application of satellite cloud photographs
Application of computer products
SOUTHERN HEMISPHERE ANALYSIS
Because of the location of the majority of our naval forces, most Aerographer’s Mates have a Northern Hemisphere orientation. Thepeculiar aspects of the Southern Hemisphere don’t come into play until we are called upon to make analyses in this area. It requires a considerable amount of effort to reorient yourself to the fact that cyclonic circulations in this hemisphere have a clockwise rotation of the winds, and anticyclonic circulations are counterclockwise. Also, the pressure pat-terns are more regular in this hemisphere, because of the absence of the large land masses present in the Northern Hemisphere. However, certain similarities do exist. For example, in both hemispheres, fronts, troughs, and lows slope toward the coldest air; ridges and highs slope toward the warmest air; isobar kinks point toward higher pressure; and lapse rate and moisture relations are unchanged. The basic differences of hemispheric analysis can be subdivided into two groups: geographical (including topographical) and dynamical.
Learning Objective: Identify the dif-ferences between Northern Hemisphereand Southern Hemisphere analysis procedures.
Aside from the greater land area of theNorthern Hemisphere, the distribution of these land masses (including ice surfaces that do not break at any season) is quite different. Only within 10° to 25° of the equator are the land mass areas of the two hemispheres com-parable. The great land masses of the Northern Hemisphere extend from subtropical to subarc-tic latitudes, with the Arctic Ocean covering most of the area north of the 65th parallel. In the Southern Hemisphere, the vast majority of the middle latitudes are covered with water. From 45°S to 65°S, it is virtually all water, with the edge of the antarctic ice cap oscil-lating seasonally near the Antarctic Circle. The arctic ice cap seldom rises more than a few feet above sea level, and areas of open water appear during the summer season. By com-parison, the topography of the antarctic ice cap rises to altitudes over 13,000 feet. Most of the area is a plateau with a mean elevation of about 10,000 feet, dropping sharply to sea level around the periphery. Only a few iso-lated areas of open water have ever been observed in the summer.
The longitudinal distribution of land andwater is also different, with two major con-tinents and oceans in the Northern Hemisphere and three each in the Southern Hemisphere. The principal topographical features of 50°S latitude are the Andes of South America and the plateau of South Africa, with its mean elevation about 5,000 feet. Australia is prac-tically without marked topographical features, and nowhere south of the equator are there any features comparable to the Alps, Urals, or Himalayas.