Have you ever noticed that sunlight...

The other day we are sitting in the office and notice that light is shining in on the wall, and the light seems to be moving up and down in waves. I have noticed this when the sun shines through the window on light colored surfaces. Is there a name for this phenomon? Someone in our office suggested that it was the heat meeting cool air in the atmosphere that caused it

I love offices where you can discuss (un)important stuff like that. :wink:
If the phenomenon is anything like what I’m thinking of, I think it has to do with sunlight-warmed air rising through slightly cooler air, yes, probably either immediately in front of or behind the window.

IIRC, warm air and cool air will each bend light slightly differently, and this effect, combined with the fact that the warm air is never in precisely the same place, accounts for the ‘waves’ seen. Does that sound right?? :slight_smile:

What you are likely seeing is refraction from the boundary from cool and warm air circulating in the room. This is because the speed of light varies with the density of air which is directly related to temperature. When light passes through a boundary beteween two regions with a different refractive index such as glass/air, air/water or cool air/warm air at anything other than a 90º angle it will bend at the interface. If the angle of light is nearly parallel to the interface it can actually reflect from the interface, this is what causes the mirage effect which can make reflected sky look like a shimmering lake in the distance.

Just to eliminate the stupidly obvious; the light entering your office window doesn’t pass through the branches of a tree first, does it?

(I mention this because I get the impression that the OP is perhaps talking about something other than heat shimmer).

Another factor that can result in moving patches of cast sunlight through a window is a light covering of wispy clouds; as these pass across the sun, they mask parts of it, effectively causing it to act like a moving light source.

Nope…this was a very fast moving wave in the light.

You mean like little ripples moving upwards through the patch of light? - if so, then yes - it’s heat shimmer (the same effect you see when you look along a hot road on a sunny day)

Oasis this way.