Mountain Climate - Mountain Geography: Physical and Human Dimensions - page 118

FIGURE 3.24 Wind behavior in relation to microtopography in the Cairngorm Mountains, Scotland.
The stippled area represents vegetation. Vertical scale is roughly equivalent to the horizontal. (A)
Air movement across a grassy tussock. (B) The movement of air over a rock with a depression
occupied by vegetation. (C) A wind-eroded bank. Note the eddies that develop to the lee of small
obstacles: Wind speed is greatly reduced in these areas and vegetation is better developed. (Ad-
apted from Warren-Wilson 1959: 417-418.)
Closed basins, even those created by dense forest cover, can trap the cold air, cre-
ating cold pockets or “frost hollows” (Clements et al. 2003; Daly et al. 2010). These
temperature inversions can reach 30°C (77°F) below the ambient atmosphere and can
persist for weeks or months, effectively trapping atmospheric contaminants until strong
enough winds can clear the air (Geiger 1965; Iijima and Shinoda 2000). These have ob-