During the spring of 1961, evaporation from snow and soil surfaces was measured in the central Rocky Mountains near Fraser, Colorado. Measurements were made in natural forest openings at 9,000 feet elevation. Evaporation from wet soil surfaces greatly exceeded evaporation from nearby snow. There was little evidence of transfer of vapor from soil to nearby patches of snow, but as areas of bare, wet soil increased and evaporation amounts from such surfaces increased, evaporation from snow decreased. It was concluded that, as greater amounts of water evaporated from soils, the vapor pressure of the air was raised sufficiently to reduce evaporation from snow. Since transfer of vapor from soil to snow appeared small at best, evaporation losses from snow and soil surfaces essentially constituted a total moisture loss from the area. RESUME Au cours du printemps 1961, I'evaporation de surfaces de neige et de sol a ete mesuree dans les Montagnes Rocheuses Centrales pres de Fraser, Colorado. Les mesures furent faites dans des clairieres a 9000 pieds d'altitude. L'evaporation de surfaces de sol humide depassait largement celie de la neige voisine. II y avait peu d'indices d'un transfert de vapeur du sol vers les surfaces enneigees, mais quand les surfaces de sol nu et humide augmentaient et que les quantites evaporees de ces surfaces s'accroissaient, l'evaporation de la neige diminuait. II en a ete dectuit que lorsque de grandes quantites d'eau s'evaporent des sols, la pression de vapeur de l'air est augmentee suffisamment pour reduire I'evaporation de la neige. Comme Ie transfert de vapeur du sol a la neige semble faible, les pertes par evaporation des surfaces de sol et de neige constituent essentiellement une perte totale d'humidite pour toute l'aire consideree. (*) Research reported here was conducted as partial fulfillment for a Master's Degree in Watershed Management,
