Final answer:
Snow remains on mountain slopes above freezing temperatures because phase changes from solid to liquid require a significant amount of heat over time. Daytime temperatures slightly above 0°C do not instantly melt snow due to the gradual absorption of heat needed for melting. Other factors like shade, altitude, and wind also influence the rate of melting.
Step-by-step explanation:
Why Snow Remains on Mountain Slopes Above Freezing Temperatures
Snow can often remain on mountain slopes even when the daytime temperatures are above the freezing point. This phenomenon occurs because snow, being the solid phase of water formed from ice crystals, requires a significant amount of heat for a phase change to occur. Even when air temperatures rise above 0°C, the snow doesn't immediately melt because melting is an energy-intensive process. The heat must be absorbed by the snow to break the bonds between the ice crystals, leading to a phase change from solid to liquid.
Moreover, the rate at which snow melts is dependent on the warmth of the air. The more the temperature increases above the melting point, the faster the heat is absorbed, thus accelerating the melting process. However, if the increase in temperature is slight or gradual, snow can remain stable for a period despite the seemingly warmer weather, particularly on mountain slopes where conditions such as shade, altitude, and wind can significantly affect temperature and melting rates.
In summary, the presence of snow on mountain slopes at temperatures above the freezing point is due to the time and amount of heat necessary to induce the melting process. It isn't an immediate transition, which is why snow patches may persist despite warmer air temperatures during the day.