The wind information obtained during this study was unreliable due to the instrumentation problems. The vertical motion is a function of the prevailing synoptic conditions, the release of latent heat by condensation, the topographic conditions, and frictional effects. Since the main interest here is the orographically induced precipitation, only vertical motion due to topographic influences is considered in this report. It is known that the majority of the precipitation which falls at Alta is orographically induced. The vertical velocity for air flowing up a slope can be computed by the well-known expression where w m is expressed in millibars per 3 hours, g is the force of gravity.
P o is nearly unity and is neglected.
Since little is known about the wind flow in and over mountainous regions, a modified value of the 700 Mb wind is used for V O . An advantage of using the wind at this level is that current and prognosticated data are readily available at this level. It was found that when the wind direction was from the 240 degree to 300 degree interval, the 700 Mb wind speed could be used directly for V o . This factor decreases the orographic lifting effect of the wind as it becomes more and more parallel to the mountain range until V O becomes nil for wind directions of 360 degrees or 180 degrees. From topographic charts of the Alta area, VH was approximated as 0.095.