Question

The snow on the mountains does not melt all at once. Give scientific reason.

Answer 1

Hint: Every year, with the beginning of the warmer summertime, the snow in the mountains starts to melt. However, it melts gradually depending on the weather conditions and not all at once. The reason for this is explained below.

Complete step by step answer:
Two primary factors control the melting of snow:
-Air temperature
-Intensity of the sun
Some secondary factors that also contribute to this process are the direction and magnitude of wind and wind flow, heat absorption properties of the nearby surfaces, snow density, etc.
The top layer of the snowpack absorbs the heat energy of the surrounding atmosphere and from the sun and causes the snow crystals to break down. As the snow is converted into water, the water drops start to flow to the ground. The warmer water drops cause some pre-melting in the upper layers but eventually leak through the snow with no major effect on its consistency. The contribution from heat absorption from direct sunlight is usually much larger than from the surrounding air.
As a result, the top layer gradually melts making streams of water flow from the mountain due to the converted snow. Hence the snow does not all melt at once since there is not enough thermal energy in the atmosphere to melt it all at once.

Note: Sudden melting of large amounts of snow can even cause flooding in some regions and often happens around the globe. The advent of climate change and global warming causes this effect to happen more frequently.