Final answer:
Sleet freezes first when sleet, freezing rain, or snow fall.
Step-by-step explanation:
Sleet, freezing rain, and snow are distinct forms of frozen precipitation, each with its unique characteristics. The key factor influencing the freezing process is the temperature profile of the atmosphere through which these precipitation types pass.
Firstly, sleet begins as snowflakes in the upper layer of the atmosphere where temperatures are below freezing. As these ice crystals fall, they pass through a layer of warmer air, causing them to partially melt into raindrops.
However, before reaching the ground, the raindrops encounter another sub-freezing layer, leading to their refreezing into tiny ice pellets. This dual melting and refreezing process in sleet formation contributes to its quicker freezing compared to freezing rain or snow.
In contrast, freezing rain forms when snowflakes melt completely into raindrops in a warm air layer aloft but encounter a sub-freezing layer closer to the ground. These raindrops freeze upon contact with surfaces, creating a layer of ice. Snow, on the other hand, remains solid throughout its descent from the cloud to the ground, bypassing the partial melting and refreezing stages observed in sleet formation.
In summary, the unique process of partial melting and refreezing in the sleet formation process, influenced by distinct temperature layers in the atmosphere, results in sleet freezing first when compared to freezing rain or snow.