<P> A katabatic wind originates from radiational cooling of air atop a plateau, a mountain, glacier, or even a hill . Since the density of air is inversely proportional to temperature, the air will flow downwards, warming approximately adiabatically as it descends . The temperature of the air depends on the temperature in the source region and the amount of descent . In the case of the Santa Ana, for example, the wind can (but does not always) become hot by the time it reaches sea level . In Antarctica, by contrast, the wind is still intensely cold . </P> <P> The entire near - surface wind field over Antarctica is largely determined by the katabatic winds, particularly outside the summer season, except in coastal regions when storms may impose their own wind field . </P> <P> Katabatic winds are most commonly found blowing out from the large and elevated ice sheets of Antarctica and Greenland . The buildup of high density cold air over the ice sheets and the elevation of the ice sheets brings into play enormous gravitational energy . Where these winds are concentrated into restricted areas in the coastal valleys, the winds blow well over hurricane force, reaching around 300 km / h (190 mph). In Greenland these winds are called piteraq and are most intense whenever a low pressure area approaches the coast . </P> <P> In a few regions of continental Antarctica the snow is scoured away by the force of the katabatic winds, leading to "dry valleys" (or "Antarctic oases") such as the McMurdo Dry Valleys . Since the katabatic winds are descending, they tend to have a low relative humidity, which desiccates the region . Other regions may have a similar but lesser effect, leading to "blue ice" areas where the snow is removed and the surface ice sublimates, but is replenished by glacier flow from upstream . </P>

When are you most likely to be effected by side winds