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Weather experiment creating dew and frost

Posted at 6:54 AM, Apr 01, 2020
and last updated 2020-04-01 07:07:41-04

GRAND RAPIDS  — Many cold mornings in the summer and winter we often see dew or frost on our cars or out on the lawn….but why does it show up and how? In today's weather experiment we are going to create frost and dew learning how temperature and moisture play a big roles in the creation of both.

Lets get started! Here is what you will need.

- 2 tin cans without lids
- Rock salt or table salt
- Crushed ice

Step 1: Fill the first tin with crushed ice about half-way up. Add 4 tablespoons of salt. Mix well for about 30 seconds and let it rest.

Step 2: Fill the other tin can with crushed ice about half-way up. Add cool tap water to just cover the ice.

Step 3: Sit back and watch the dew and frost form!

The frost will form on the tin can with the ice and salt mixture while the dew will form on the tin can with the ice and water mixture. It's all based on temperature and moisture!

The frost forms from the salt absorbing the water to make a salt solution. For this to happen the salt has to melt the ice into water. This process requires heat which actually comes from the ice itself ironically enough. The chemical reaction between melting the ice and the salt actually makes the whole mixture cooler. The mixture inside this can gets below the freezing mark which then makes the moisture from the air on the outside of the can to freeze and become a solid. This forms the frost!

The dew forms in a more simple set up. The mixture of just ice and water melting is right at the freezing mark at 32 degrees Fahrenheit. The temperature then on the outside of the can is warm which causes the dew to form.

In both cases it depends on the moisture content in the air and temperature that is available in the environment. Frost and dew are both water vapor and the water vapor getting past the freezing point to work into the solid state forms frost. When the water vapor just hoovers around the freezing mark working into the liquid state it forms dew.

There you go! You created dew and frost right before your eyes! Send our meteorologist Candace Monacelli your pictures doing this experiments at home! She will feature future meteorologists on my Facebook page daily!