Final answer:
Condensation forms on cold surfaces because they cause the air to cool below its dew point. Sublimation occurs with solid H₂O even below 0°C. The unique properties of water's density and expansion upon freezing have important environmental and technological implications.
Step-by-step explanation:
Condensation occurs when a gas turns into a liquid. It forms most rapidly on the coldest object in a room, such as a glass of ice water, because the cold surface cools the air around it below its dew point, causing water vapor to condense into liquid water.
When it comes to sublimation, solid H₂O or ice can change directly into water vapor without becoming a liquid first, a process which can occur even at temperatures below 0°C. Snowflakes are made up of ice crystals and represent the solid phase of water. Significant heat exchange is required for snow to melt, with warmer air accelerating this process.
When discussing large bodies of water, the fact that ice is less dense than liquid water means that surfaces freeze first, forming an insulating layer that protects aquatic life in the unfrozen water beneath. To understand how freezing impacts the environment and technology, one must consider the expansion of water upon freezing.