Explanation:

In the upper parts of the Himalayas, precipitation is mostly in the form of snowfall. This can be attributed to several factors:

1. Elevation:
The Himalayas are the highest mountain range in the world, with many peaks exceeding 8,000 meters in height. As one climbs higher in elevation, the temperature decreases. At higher altitudes, the average temperature is below freezing point throughout the year. This cold temperature favors the formation and maintenance of snow.

2. Orographic Lifting:
The Himalayas act as a barrier to the moisture-laden winds coming from the Indian Ocean. As the warm and moist air approaches the mountains, it is forced to rise due to the topography. This upward movement causes the air to cool, leading to condensation and the formation of clouds. These clouds then release moisture in the form of snowfall when the temperature is below freezing.

3. Cold and Dry Climate:
The Himalayas create a rain shadow effect on the northern side, resulting in a cold and dry climate. As the moisture-laden air moves towards the Himalayas, it releases most of its moisture on the southern side, leaving less moisture for the northern side. This reduces the amount of rainfall and increases the likelihood of snowfall.

4. Monsoon Season:
During the monsoon season, the Indian subcontinent receives heavy rainfall. However, as the moist air encounters the Himalayas, it is forced to rise and cool. This cooling leads to the condensation of moisture, which falls as snowfall in the upper regions of the mountains.

5. Snowfall Benefits:
The prevalence of snowfall in the upper parts of the Himalayas has several benefits. It contributes to the formation and maintenance of glaciers, which act as a natural water source for rivers in the region. Snowfall also helps to regulate the temperature in the surrounding areas and provides habitat and moisture for various flora and fauna.

In conclusion, the upper parts of the Himalayas experience snowfall as the primary form of precipitation due to their high elevation, orographic lifting, cold and dry climate, interaction with monsoonal winds, and numerous associated benefits.