Final answer:
Snow is a solid form of water that requires heat to change phases and melt. It can also sublimate, transitioning directly from solid to gas, especially under certain conditions like high winds or low pressure at high altitudes.
Step-by-step explanation:
Snow, a form of precipitation, comprises transparent ice crystals that form the solid phase of water. Due to the required significant heat for phase changes, snow does not melt instantaneously. It takes time for the heat to be absorbed from the air, particularly when the air temperature is above 0°C. The process of melting accelerates with higher air temperatures because the heat exchange is quicker.
Additionally, snow can undergo a process known as sublimation, where it transforms directly from a solid to gas without becoming liquid, which is common at temperatures below water's melting point. This process can speed up due to wind and the lower atmospheric pressure at elevated altitudes. The opposite process, where gas turns directly into solid, is called deposition. An example of deposition is the formation of frost.
These phases and transitions of snow are important considerations for activities such as skiing or managing ice and snow on roads and are subject to the melting point of the solid and the freezing point of liquids.