Book 13, Question 84
Why Does Frost Sparkle?
Frost and fresh snow are made of tiny ice crystals with flat, shiny faces. Each face works like a little mirror. When you move, different faces tilt toward your eyes, and each flashes a bright spark.
More fun facts
- Frost is a covering of ice crystals formed when water vapor deposits onto a surface colder than 0 degrees Celsius, or 32 degrees Fahrenheit.
- The World Meteorological Organization defines hoar frost as a deposit of ice made by the deposition of water vapor from the surrounding air.
- Frost forms when a surface cools below the frost point, the temperature at which the air is saturated with water vapor over ice.
- On clear, calm nights, the ground can fall below freezing while the official air temperature is still above freezing.
- Frost crystals may form on objects near the ground, like a bush or a car windshield, once they cool below the frost point.
- The World Meteorological Organization lists two kinds of hoar frost: hoar frost proper and advection hoar frost.
Sources: National Weather Service, cloudatlas.wmo.int
Questions kids ask
Why does frost often melt first in the sunny spots?
Sunlight warms those surfaces, so their ice crystals melt sooner.
Is frost the same as frozen dew?
Not exactly. True frost grows as ice straight from water vapor in the air.