FIGURE 6.14 Except at the equator, a free-moving object heading either east or west (or any other direction) will appear from the earth to deviate from its path as the earth rotates beneath it. The deviation (Coriolis force) is greatest at the poles and decreases to zero at the equator. Fig. 6-14, p.153

FIGURE 6.15 Above the level of friction, air initially at rest will accelerate until it flows parallel to the isobars at a steady speed with the pressure gradient force (PGF) balanced by the Coriolis force (CF). Wind blowing under these conditions is called geostrophic. Fig. 6-15, p.154

FIGURE 6.16 The isobars and contours on an upper-level chart are like the banks along a flowing stream. When they are widely spaced, the flow is weak; when they are narrowly spaced, the flow is stronger. The increase in winds on the chart results in a stronger Coriolis force (CF), which balances a larger pressure gradient force (PGF). Fig. 6-16b, p.155

FIGURE 6.17 Winds and related forces around areas of low and high pressure above the friction level in the Northern Hemisphere. Notice that the pressure gradient force (PGF) is in red, while the Coriolis force (CF) is in blue. Fig. 6-17, p.155

subgeostrophic subgeostrophic Fig. 6-8b, p.148 FIGURE 6.8 (b) The upper-level (500-mb) map for the same day as the surface map. Solid lines on the map are contour lines in meters above sea level. Dashed red lines are isotherms in °C. Arrows show wind direction. Notice that, on this upper-air map, the wind blows parallel to the contour lines. Fig. 6-8b, p.148

Geostrophic wind Fig. 6-19a, p.159 FIGURE 6.19 (a) The effect of surface friction is to slow down the wind so that, near the ground, the wind crosses the isobars and blows toward lower pressure.(b) This phenomenon at the surface produces an outflow of air around a high. Aloft, the winds blow parallel to the lines, usually in a wavy west-to-east pattern. Fig. 6-19a, p.159

FIGURE 6.19 (a) The effect of surface friction is to slow down the wind so that, near the ground, the wind crosses the isobars and blows toward lower pressure.(b) This phenomenon at the surface produces an outflow of air around a high. Aloft, the winds blow parallel to the lines, usually in a wavy west-to-east pattern. Fig. 6-19, p.159

divergence convergence H L L H convergence divergence

H L L H divergence convergence COOLING ALOFT UNSTABLE convergence

H L L H divergence convergence COOLING ALOFT UNSTABLE WARMING ALOFT

0° FIGURE 6.23 Wind direction can be expressed in degrees about a circle or as compass points. Fig. 6-23, p.161

FIGURE 6. 26 A wind vane and a cup anemometer FIGURE 6.26 A wind vane and a cup anemometer. These instruments are part of the ASOS system. (For a complete picture of the system, see Fig. 3.17, p. 74). Fig. 6-26, p.162

FIGURE 6.27 The aero vane (skyvane). Fig. 6-27, p.162

Tucson Radiosonde Profile Winds Source: http://www.rap.ucar.edu/weather

Satellite-derived Winds Source: http://www.nesdis.noaa.gov

Wind profiler Source: http://www.profiler.noaa.gov/npn/profiler.jsp