Take a walk on a windy day, or just stand outside for a few minutes.
Talk about the wind with your child and explore what it does. Can you see the wind? How do you know it's blowing? What does it do to objects and the people around you? What does it do to the trees? How about flags and electric wires?
Can you hear the wind? What does it sound like when it blows through the leaves and against the windows?
How does the wind feel? Can you feel it blowing against your own body and clothes?