Altitude Effect on the Deuterium Content of the Local Rains and Snows in the Himalayas

To observe the altitude effect on the deuterium content of precipitation, two sampling projects were conducted to collect precipitation waters. One is long term sampling by simple rain gauges installed along mountain slopes. Another is simultaneous daily precipitation sampling at two different altitudes.Both of them have sufficient altitude differences, about 1000 m for each.The result could not be explained either by the depletion or by the enrichment of heavy isotopes in the precipitation caused by altitude.It can be regarded as some kind of precipitational amount effect, but still the whole process cannot be grasped.