Chapter 8 Investigation B

At the same time, the air temperature outside the aircraft ________.

falls

The 500-mb map (Figure 4) also shows that, where contour lines are relatively close, such as across the U.S. Plains States, wind speeds are relatively ________ compared to where contour lines are more widely spaced. This principle corresponds to the similar relationship between the spacing of isobars and wind speeds on surface maps.

faster

The station identified in Table 2 with the highest height and warmest temperature was ________.

Albuquerque, NM

From Table 2, consider stations A, B, and C located on the 500-mb map: One station in western New York, another in north-central New Mexico, and yet another in eastern Wisconsin. Examining those stations' data on the map identifies Station A in Table 2 to be ________, Station B to be ________, and Station C to be ________.

Albuquerque, NM; Buffalo, NY; Green Bay, WI

On the same map, there is evidence of a broad ________ across the region from the Great Lakes to the Gulf of Mexico.

ridge

At upper levels, the wind directions are also related to the contours. That is, especially where winds are relatively fast, the winds are generally ________.

"parallel" to the contours

Upper air features result from cooler temperatures in the air column between the surface and 500 mb. The lowest500-mb heights are generally associated with ________ latitude stations. However, when there is a highly amplified wave pattern, as in Figure 4, that latitude correlation may not hold true. Nashville, TN, Green Bay, WI, and International Falls, MN are located along a similar north-south axis, but in Figure 4 Green Bay has the lower height at 500-mb of pressure, despite being located south (lower latitude) of International Falls.

higher

Contour lines on constant-pressure upper-air maps separate regions that have higher altitudes from those areas that have lower altitudes than the value of that contour line. In Figure 2, the area to the south of the 5760-m contour across the southern U.S. is where 500-mb altitudes are among the ________ on the map. Conversely, on the same map, the area north of the 5460-m contour line from eastern Washington State to northern Maine is a region where 500-mb altitudes are the lowest.

highest

Compare the surface (Figure 3) and 500 mb (Figure 4) wind speeds in a general west-east band across the middle of the country at the same locations at 12Z 24 OCT 2017. The wind speed comparison shows that as altitude in the atmosphere increases, wind speeds generally ________. This relationship results in part from the absence of friction in the middle and upper atmosphere.

increase

The 500-mb map and other constant-pressure upper-air maps are actually topographic maps that give form or shape to imaginary surfaces on which the air pressure is everywhere the same. That is, the contour pattern reveals the "hills" and "valleys" of the constant-pressure surface. The contour pattern of the Figure 2 map indicates that, in general, the 500-mb surface (the surface where the air pressure is everywhere 500 mb) is at a ________ altitude in southern Canada than in the southern U.S.

lower

The wave pattern of most of the contour lines on the Figure 2 map consists of topographic ridges and troughs, that is, elongated crests and depressions, respectively. A ________ appears on the Figure 2 map over the region from the western Canada to southern California and Arizona.

trough

On the 500-mb map, the plotted report for Great Falls shows that, at the 500-mb pressure level over the station, the temperature was ________°C.

-14

The dewpoint at 500 mb over Great Falls was ________°C.

-19

The highest surface wind speeds at map time were along the region of strongest horizontal pressure gradient across the High Plains States. The wind speed at Minneapolis in eastern Minnesota, and Kansas City, Missouri (western Missouri), was about ________ knots.

15

On the Figure 2 map, the lowest height reported at an individual station for a pressure reading of 500-mb was ________ m.

5410

The wind at Great Falls was generally from the northwest at about________ knots. [Note: When winds of 50 knots or greater are reported, a pennant is used on the station's wind shaft for a 50-kt increment along with the appropriate number of long and short "feathers."]

55

Recalling that the heights plotted at individual stations on 500-mb maps are in tens of meters (place a 0 to the right of the three plotted digits), the coded height at Great Falls, in western Montana, ("584") indicated 500 mb occurred at ________ meters above sea level.

5840

Solid lines on the 500-mb map join locations where the 500-mb pressure level is at the same altitude. These lines, called contours of height, are drawn here at intervals of 60 m. The coded height values on the map are in tens of meters. On the map, contour values are labeled in whole meters. The highest reported 500-mb height at any individual station on the Figure 2 map was ________ m.

5840

Compare the temperatures for Stations A, B, and C in Table 2. As you recall from Investigation 5B, the relation of column temperatures to heights of pressure surfaces was examined using conceptual "pressure blocks." The 500-mb temperature, reflective of the temperature of the column beneath that level, was lowest at ________.

Green Bay

Using the 500-mb station values from Table 2 as well as the contour pattern, compare the reported station heights at Albuquerque, in north-central New Mexico, Buffalo in western New York, and Green Bay in eastern Wisconsin. The 500-mb height was lowest over ________.

Green Bay

The contour pattern of the 500-mb map has ________.

a deep trough from the Great Lakes to the Gulf of Mexico

Surface wind directions at stations near isobars were generally oriented ________ to their nearby isobars. These wind patterns were a result of the combination of horizontal forces acting on air near the surface, including the horizontal pressure gradient, Coriolis, and friction forces.

at an angle

Therefore, the air below the 500-mb region of lowest heights in Figure 2 must be ________ than the air below the surrounding higher 500-mb surfaces.

colder

The overall circulation pattern of surface winds about the strong low-pressure center from the Great Lakes region into the Mississippi River Valley as seen from above was generally ________. This pattern was a result of the combination of forces including friction at Earth's surface.

counterclockwise and inward

The upper air station model also gives the air temperature at 500 mb. The plotted station data show that, as latitude increases (i.e. moving poleward), the general decline of 500-mb temperatures is accompanied by a(n) ________ in the altitude of the 500-mb surface.

decrease

Suppose that at 00Z 4 DEC 2017 you board an airplane and fly non-stop directly from Miami, the southern-most reporting station in Florida, to Great Falls, the western station in Montana. En route, the plane cruises along the 500-mb surface. Flying from Miami to Great Falls, the aircraft's actual cruising altitude ________.

decreases

The station identified in item 26 ________ coincide with the lowest height of the three stations identified in Table 2 at 500 mb.

did

A relationship exists between the orientation of height contours and wind direction on 500-mb maps, especially at higher wind speeds. As seen in Figure 2 across the Utah to New Jersey area of the U.S., wind directions are generally ________ to nearby height contour lines. This is because the frictional forces acting on moving air at and near Earth's surface diminish rapidly with height and are essentially absent in determining middle and upper atmosphere motions.

parallel