Although these data were collected from a limited period during one winter, they are indicative of the erosion process in the dryland Northwest. Air temperatures had averaged 23 F for the previous week. A warm moist air mass entered the area about 11 p.m. on Jan. 11. Condensation adds a small amount of water, but more importantly it adds heat. As water condenses it gives up heat.
Heat given up by condensation on a snowpack accelerates snowmelt.
0.4 4.7 0.3 Gilliam 4 2.5 6.0 13.2 Morrow 2 0.3 5.2 0.5 l Cumulative precipitation from December 1 to February 25. No runoff observed until January 12. Clearly frozen soils play a key role in the erosion process. To fully assess this role, we must consider the frequency and duration of soil frost. Average and observed soil and weather conditions at Pendleton for November through March are shown in Table 4.