When the weather gets cold, a tiny coat of ice covers surfaces near the ground, such as grass, leaves and sometimes cars.

It doesn’t happen every cold night, but the ice children may see while waiting for the bus early in the morning is called frost.

It’s frozen dew that forms when the air temperature cools to the dew point temperature. When the two meet, the relative humidity is equal to 100%.

Watch the video above for more on how frost forms.