1. The Water in the Air

2. First, let’s name the three states of matter. Solid Liquid Gas When we think of water, of what state of matter do we usually think? Liquid

3. Can water ever be a solid? Yes, when it is frozen into ice. Can water ever be a gas? Yes, when it is heated, it becomes water vapor.

4. What is the earth’s atmosphere made of? The atmosphere (air) is a mixture of gases such as nitrogen, oxygen, carbon dioxide, and water vapor. So, do we agree that there is water in the air around us although it cannot be seen?

5. How does water get into the air? Have you noticed what happens to puddles after it rains? What would happen if I washed the blackboard with water? What happens when someone hangs out the wet laundry? Where would all this water go? Into the air!

6. This process is called evaporation! Water absorbs heat (energy) as it evaporates. The more heat energy that it absorbs, the faster it will evaporate. Let’s begin our investigation with some evaporation activities.

7. Can we remove water from the air?

8. Yes! It is called condensation. Have you ever had a cold soft drink in a cup? What happened on the outside of the cup? Where did the water come from? The air! Heat energy must be removed from the air in order for the water vapor to become a liquid. Let’s remove water from the air with a condensation activity.

9. What are clouds? Clouds are made of water vapor that has been cooled at high altitudes and condensed into millions of tiny water droplets.

10. The amount of moisture or water vapor in the air is called humidity. Today, we are going to investigate relative humidity. Relative humidity is the amount of water in the air compared to the amount of water that could be in the air at a given temperature.