Humidity Lesson for Kids

Instructor: Kelly Beaty

Kelly has taught fifth grade language arts and adult ESL. She has a master's degree in education and a graduate certificate in TESOL.

Did you know that water can be found in a solid, liquid, or gas form? In this lesson, we learn about humidity, or how much water is in the air. We will learn what humidity is, where it comes from, the way it is measured, and the way it affects our atmosphere.

Invisible Water

Have you ever felt the air just outside of a hot bath or shower? It feels wet, but you cannot see any water in the air.

There really is water in the air, but it is in the form of a gas. This kind of water is called water vapor. You can't see it, but you can feel it.

The water vapor that is in the air is called humidity.

Where Does Humidity Come From?

Water vapor comes from natural water sources and living creatures on the Earth. When water evaporates from lakes, ponds, oceans, rivers, and other bodies of water, the result is water vapor. Water in this gaseous state causes more humidity in the air.

Humans and animals also produce water vapor when they breathe. When we breathe out, the air we exhale has some water vapor in it. This humidity goes out into the world and can have an effect on humidity levels.

Plants give off water vapor into the atmosphere, too. Through a process called transpiration, the extra water that plants have in them is released into the air.

All of these sources - humans and animal respiration, evaporation, and transpiration - send water vapor into the air around us. This causes humidity to go up.

Measuring Humidity

Humidity is measured as a percentage, or a part, of all of the air in a certain area.

Reporting Humidity

In this picture, you can see the words 'Humidity 53%,' which is read as ''Humidity fifty-three percent.'' This means that out of all of the air being measured (100% of it), 53 out of 100 parts are made up of water vapor. The air in this report would be completely filled with water vapor if the humidity were 100%.

This way of reporting humidity is called relative humidity. It depends on the air that is being sampled. Warm air can hold more humidity than cold air can, so 53% humidity on a cold winter day would mean more water vapor than 53% humidity on a hot summer day.

Humidity in Our World

The air we take into our bodies has different amounts of humidity in it every day. Air temperature, plant transpiration, human breathing, and natural water sources all cause these day-to-day changes.

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