In Figure 4B-1, as is common in winter, a very strong contrast in air masses existed from Canada to Florida, an exceedingly cold Arctic air mass plunged southward. Temperatures in the upper Midwest were well below zero, yet ahead of the fronts, along the Gulf of Mexico, temperatures were well into the 60 s and 70s. Isotherms were close together along the front from the Rocky Mountains to the Southern Plains. 1. Compare the number of isotherms across Kansas to Texas in Figure 4B-1. There is roughly a F contrast. a. 10 b. 30 c. 60 d. 80 There are multiple high pressure centers in Figure 4B-1 which means there are multiple cold air mass regions: in the High Plains, along the East Coast, and eastern Canada. Of those, the high in the Northern High Plains is the coldest. 2. In Figure 4B-1, the leading edge of the Arctic air mass was across northern Texas and the Panhandle. From roughly Tulsa, OK southwest to Dallas/Ft. Worth and Midland, TX, a(n) front curved southwestward, with bitterly cold air to the north of the front and milder, warmer air to the south and west. The greatest thermal contrast was from Midland, TX to Wichita, KS. a. warm b. stationary c. cold d. occluded 3. From west Texas northwest up into Denver, CO, the front was a(n) front. a. cold b. stationary c. warm d. occluded e. none of the above 4. Examine the temperature and wind direction in El Paso and Midland, TX. The direction of winds at these locations brought air flow perpendicular to the 7 0 F isotherm, which would be an example of advection in West Texas. a. warm air b. cold air c. neutral 5. Winds at Wichita, KS and Oklahoma City, OK were from the north at about 15 kts. Wichita, specifically, was located right ahead (south) of the F isotherm lines. a. 10 b. 20 c. 30 d. 40 6. The wind flow at Wichita oriented almost directly across the isotherms, from temperature. Stations north of the front, including Kansas City, MO and Des Moines, IA, displayed this same pattern of temperatures and air flow. a. colder to warmer b. warmer to colder c. similar d. none of the above 7. From this wind flow, you can conclude that air advection occurred. This flow dominated the Central Plains from Iowa southward. a. cold b. warm 8. Compare the Wichita advection pattern to that of Midland and El Paso. The wind flow and air mass advection on opposing sides of fronts and low pressure centers display air flow advection patterns, which is consistent with the circulation expected around a low pressure center. a. similar b. opposing .