Snow fog, also known as ice fog or steam fog, is a type of fog that forms when very cold air moves over relatively warmer water or moist ground, especially when there is snow on the ground.
Here's a more detailed explanation:
-
The Process: Warm, moist air blows over a cold surface like snow-covered ground. This causes the air to cool rapidly. As the air cools, its ability to hold moisture decreases. The water vapor in the air then condenses, forming tiny water droplets or ice crystals that are suspended in the air, creating the fog.
-
Key Conditions:
- Cold Air: Temperatures usually need to be well below freezing for snow fog to form, often -10°C (14°F) or colder.
- Moisture Source: The presence of snow, open water (like lakes or rivers), or saturated ground provides the necessary moisture.
- Temperature Difference: A significant temperature difference between the air and the moisture source is crucial for rapid cooling and condensation.
-
Characteristics: Snow fog is often dense and can significantly reduce visibility. It can also contain ice crystals, making it feel sharp on the skin.
-
Examples: Snow fog is common in arctic and subarctic regions, especially near open water sources or industrial areas that release water vapor. You might also see it in areas with heavy snowfall where the ground remains saturated.
