Have you ever looked at something on the horizon and it’s all shimmery and wavy and won’t hold still? That’s because air (and moisture in the air) diffracts light. And the air is not still, either. When you’re looking an incredibly small object that’s extremely far away the effect is rather like trying to see through one of those pebble textured glass shower doors, except if it were moving and the object you were looking at were the size of a gnat. And also several miles past the door.
Just to add to this, air at different temperatures and moisture levels bends light to different degrees, which is why the layers and pockets of air that form our atmosphere make stars shimmer. It’s partially why astronomers are so eager to get telescopes into space (like Hubble and the James Webb), since the lack of this effect lets them resolve much smaller light sources than you could hope to beneath the atmosphere.
That’s basically how I’ve always pictured it, like in my mental physics playground or whatever, the many, many particles may not be dense when you take a small sample (like a cubic foot of air or something) but through miles of atmosphere it adds up and the light has lots to bounce around and off of before it gets to you. Do I basically have that right? That comment someone added makes me think im understanding it right but maybe not explaining my understanding quite right, but maybe you get what I’m trying to say.
Yes, and also different patches of air are different densities because of temperature, or humidity, and they’re neither even nor consistent nor still. Convection makes the atmosphere bubble, wind makes it shear, and all the rest of it. The air itself acts as a lens, and a very inconsistent and unpredictable one at that.
Similar just the impact of dust over a large enough distance.
Try going up to the top of, say, a 50 storey building in a moderately polluted city during a fairly still, warm, dry spell of weather and look down at the ground.
It’ll likely look a lot more dusty than from street level.
Have you ever looked at something on the horizon and it’s all shimmery and wavy and won’t hold still? That’s because air (and moisture in the air) diffracts light. And the air is not still, either. When you’re looking an incredibly small object that’s extremely far away the effect is rather like trying to see through one of those pebble textured glass shower doors, except if it were moving and the object you were looking at were the size of a gnat. And also several miles past the door.
Just to add to this, air at different temperatures and moisture levels bends light to different degrees, which is why the layers and pockets of air that form our atmosphere make stars shimmer. It’s partially why astronomers are so eager to get telescopes into space (like Hubble and the James Webb), since the lack of this effect lets them resolve much smaller light sources than you could hope to beneath the atmosphere.
That’s basically how I’ve always pictured it, like in my mental physics playground or whatever, the many, many particles may not be dense when you take a small sample (like a cubic foot of air or something) but through miles of atmosphere it adds up and the light has lots to bounce around and off of before it gets to you. Do I basically have that right? That comment someone added makes me think im understanding it right but maybe not explaining my understanding quite right, but maybe you get what I’m trying to say.
Yes, and also different patches of air are different densities because of temperature, or humidity, and they’re neither even nor consistent nor still. Convection makes the atmosphere bubble, wind makes it shear, and all the rest of it. The air itself acts as a lens, and a very inconsistent and unpredictable one at that.
Similar just the impact of dust over a large enough distance.
Try going up to the top of, say, a 50 storey building in a moderately polluted city during a fairly still, warm, dry spell of weather and look down at the ground.
It’ll likely look a lot more dusty than from street level.