How come the air shimmers in summer?
It was quite warm in Germany last week, so Mika and I went outside a lot and made the most out of the good weather. We noticed that when you look at the streets, the air above them shimmers! It’s as if the street is getting a bit dizzy from the heat. We wondered, why is that? Mika and I asked Phillip Eisenhuth about this phenomenon, and he explained it to us. We learned, that it’s not the road that gets dizzy, nor us humans, but the air! This is because the sun’s power heats up the street in summer, which then quickly becomes too warm and releases the heat into the air above. The heat energy supplied causes the air particles to start dancing, each at its own pace and direction. It’s just like with people; if you give them too much energy (lots of chocolate ice cream, for example), they can feel restless and want to get rid of this energy quickly – do sport, play or dance. And that’s exactly what the air particles do. When we look across the street, we see many of these air particles together at once, dancing with each other, around each other and on top of each other.
When light shines through these dancing air masses, it bends. Imagine you are walking through shopping streets full of people and they all want to go somewhere else. To avoid bumping into them, you avoid the people and no longer walk in a straight line, but zigzag. And that’s exactly what the light does when it shines through the warm, dancing air masses; it’s called refraction. The background appears to us as if it is moving and flickering, but it is the warm air that is moving and refracting the light in front of our eyes.
This thing doesn’t just happen over roads, I’ve found out. If you look toward the horizon on a warm, clear summer night, you might even see the stars twinkling. But once again (sadly!), those aren’t stars dancing in the sky – it’s the warm air moving around, trying to let go of the heat from the day. This can even change the color of the stars, so you’ll see red, white, yellow, and blue twinkling stars. Isn’t that cool? I’ll definitely watch out for that the next time I see a sky full of stars!
