APOD: Unusual Red Glow Over Minnesota (2009 Feb 17)

[aristarchusinexile]

I think it's sunset light coming in from the window (or even two windows) on the other side of the plane .. you can see part of the windowframe as the 'L' in the left side blaze of light .. the image of that window is cast onto the window nearest the observer, the colour also maybe reflecting in the moisture in the air below the aircraft, but I don't think so, I think it's a double reflection, from two windows, on the one window.

[apodman]

orange rain

Does nobody realize that the artist formerly known as the artist formerly known as Prince is from Minnesota? This effect may be a defective prop escaped from a Purple Rain stage show.

[Chris Peterson]

I think it's sunset light coming in from the window (or even two windows) on the other side of the plane .. you can see part of the windowframe as the 'L' in the left side blaze of light .. the image of that window is cast onto the window nearest the observer, the colour also maybe reflecting in the moisture in the air below the aircraft, but I don't think so, I think it's a double reflection, from two windows, on the one window.

The Sun was on the same side of the plane as the window, so it couldn't have come from windows on the opposite side.

Again, we need to keep in mind the conditions under which the photographer took the image. He looked outside and saw a bright glow, which he photographed. I find it hard to believe that he would have been fooled by a reflection off the window.

[geckzilla]

Oops... I meant geckzilla, NOT geekzilla. My apologies!

(You must be a herper.)

I don't know enough about reptiles to really qualify for the title of herpetologist but I do enjoy them and animals quite a lot. As usual I know just enough to be dangerous and not enough to be a professional. No offense taken. You aren't the first to do that and I am quite a geek anyway.

[neufer]

If it actually is outside (and not an out of focus window reflection)...

My main objection to this idea is that to me, the orange area is in clear, sharp focus. It doesn't appear in the least unfocused. It contains high frequency structure.

It seems like most of the "high frequency structure" comes from the underlying patterns of buildings on the ground.

...my guess is that it is some kind of contrail effect...possibly left over from a previous jet.

I can't say that I've ever seen a jet leave something like a persistent cloud behind while at low altitude. But I've seen a number of natural clouds that look just like this, and a few of them lit up orange by sunset, also looking just like this. A natural cloud/virga formation seems a more parsimonious explanation than something artificial.

PARSIMONIOUS, a. Sparing in the use or expenditure of money; covetous; near; close. It differs from frugal, in implying more closeness or narrowness of mind, or an attachment to property somewhat excessive, or a disposition to spend less money that is necessary or honorable.

[apodman]

I thought contrails appeared at the tropopause (the boundary layer between troposphere and stratosphere, at a much higher altitude than the subject matter in this photo) where it is very cold (even in Minnesota terms). An old jet fighter pilot once told me he would lurk just below the tropopause waiting for the enemy to descend through it and show himself with his contrail.

[geckzilla]

I thought I might post some links to various photos of sunset reflections in plane windows that show vaguely similar patterns to the original photo. So far it's much more difficult to find them than it was the orange rain and they aren't nearly as similar.

scratches
http://www.flickr.com/photos/toddbox/288835117/

smudges
http://www.flickr.com/photos/jhirsch/2503890504/

flares? refractions? reflections?
http://www.flickr.com/photos/bertobox/194939486/

smudgy filaments. possibly the closest so far. The biggest difference is that the window itself is in focus rather than the terrain. So it's not very similar at all in that regard.
http://www.flickr.com/photos/schuberts/ ... 0/sizes/l/

Here's a photo where the clouds are clearly the orange blobs and have nothing to do with reflections
http://www.flickr.com/photos/iamkimiam/1077718212/

More orange rain from a plane, just not nearly as striking as the APOD
http://www.flickr.com/photos/chicanerii/2265141492/

Here is a blurred reflection from a window with the ground in focus. However, no orange in the reflection. No sunset.
http://www.flickr.com/photos/liz/59464015/

This is clearly a reflection of someone's shirt and the chair:
http://www.flickr.com/photos/jabrink/1463465441/


Oh well, that's enough devil's advocate for me.

[Chris Peterson]

It seems like most of the "high frequency structure" comes from the underlying patterns of buildings on the ground.

That's not the structure I'm referring to. I'm talking about the linear, illuminated structures running through the cloud, which look identical to virga or rain sheets.

PARSIMONIOUS, a. Sparing in the use or expenditure of money; covetous; near; close. It differs from frugal, in implying more closeness or narrowness of mind, or an attachment to property somewhat excessive, or a disposition to spend less money that is necessary or honorable. :roll:

I expect you know I meant this in its usual scientific sense:

In science, parsimony is preference for the least complex explanation for an observation. This is generally regarded as good when judging hypotheses. Occam's razor also states the "principle of parsimony"; however, parsimony is a preference rather than a general principle.

[ufosvahn]

This picture reminds me of the following article från October 2008:
http://www.thisislondon.co.uk/standard/ ... xpand=true
Maybe the answer could be the same.

Clas Svahn
Stockholm

[neufer]

This picture reminds me of the following article från October 2008:
http://www.thisislondon.co.uk/standard/ ... xpand=true
Maybe the answer could be the same.

Clas Svahn Stockholm

Very Interesting; thanks, Clas.

[neufer]

PARSIMONIOUS, a. Sparing in the use or expenditure of money; covetous; near; close. It differs from frugal, in implying more closeness or narrowness of mind, or an attachment to property somewhat excessive, or a disposition to spend less money that is necessary or honorable.

I expect you know I meant this in its usual scientific sense:
In science, parsimony is preference for the least complex explanation for an observation. This is generally regarded as good when judging hypotheses.

The least complex explanation probably wouldn't include the word "parsimonious."

Occam's razor also states the "principle of parsimony"; however, parsimony is a preference rather than a general principle.

Then what do you make of the photographer Tyler Blessing's comment: "Try not to cut yourself on Occam's razor!" ?

I'm talking about the linear, illuminated structures running through the cloud, which look identical to virga or rain sheets.

Well, virga or cloud perhaps, but it tain't rain!

Actual raindrops (that are big enough to fall) scatter light very poorly
except forwards, backwards & rainbows...which is why we CAN see rainbows:
http://antwrp.gsfc.nasa.gov/apod/ap070912.html
http://antwrp.gsfc.nasa.gov/apod/ap060702.html

And which is also why the following examples
must be low clouds or dissipating fog and NOT RAIN:
http://farm4.static.flickr.com/3200/268 ... 0397b1.jpg
http://tinyurl.com/dk26zy
http://tinyurl.com/cnk6kb

Real "Orange Rain" :

[Chris Peterson]

I'm talking about the linear, illuminated structures running through the cloud, which look identical to virga or rain sheets.

Well, virga or cloud perhaps, but it tain't rain!

Virga and rain are one and the same thing, except that the former term is used for rain that evaporates before it reaches the ground. Their optical properties are the same. I'm inclined to think this is virga, since I think with rain the ground would be less clear, but since we're really only seeing the part that's illuminated, it's hard to say for sure. The structure shows droplet sheeting, which isn't something you'd normally find in clouds. Of course, there's an ill defined area where clouds and rain overlap.

Actual raindrops (that are big enough to fall) scatter light very poorly
except forwards, backwards & rainbows...

Well, we could be looking at nearly total forward scatter here. The Sun isn't far off-axis from the direction of the shot. However, you've neglected refraction and internal reflection. Raindrops do refract and reflect light as well, which may be what's producing this effect. I have seen this exact effect from the ground in obvious virga, so there's no doubt in my mind that this could be the same.

[bystander]

Well, virga or cloud perhaps, but it tain't rain!

I thought virga is rain or snow that doesn't reach the ground.

virga: (weather) Rain or snow that is dissipated in falling and does not reach the ground, commonly appearing in trails descending from a cloud layer.

[neufer]

I'm talking about the linear, illuminated structures running through the cloud, which look identical to virga or rain sheets.

Well, virga or cloud perhaps, but it tain't rain!

Virga and rain are one and the same thing, except that the former term is used for rain that evaporates before it reaches the ground. Their optical properties are the same. I'm inclined to think this is virga, since I think with rain the ground would be less clear, but since we're really only seeing the part that's illuminated, it's hard to say for sure. The structure shows droplet sheeting, which isn't something you'd normally find in clouds. Of course, there's an ill defined area where clouds and rain overlap.

Outside of the ultra dry southwest, virga almost always refers to SNOW that doesn't reach the ground.

Evaporating virga rain might include drops small enough to Lambert scatter a little:
http://antwrp.gsfc.nasa.gov/apod/ap080529.html
but this seems unlikely in this bright orange Minnesota situation.

Actual raindrops (that are big enough to fall) scatter light very poorly
except forwards, backwards & rainbows...

Well, we could be looking at nearly total forward scatter here.

We are certainly NOT looking at nearly total forward scatter here.
The Sun is due west-south-west while we are looking DOWN and to the northwest.

However, you've neglected refraction and internal reflection. Raindrops do refract and reflect light as well, which may be what's producing this effect.

I've NOT neglected refraction or internal reflection... nor have these APOD's:
http://antwrp.gsfc.nasa.gov/apod/ap070912.html
http://antwrp.gsfc.nasa.gov/apod/ap060702.html

I have seen this exact effect from the ground in obvious virga, so there's no doubt in my mind that this could be the same.

Was it rain virga or snow virga?

[neufer]

virga: (weather) Rain or snow that is dissipated in falling and does not reach the ground,
commonly appearing in trails descending from a cloud layer.

Not a lot of trials/tails in http://apod.nasa.gov/apod/ap090217.html

<<Cirrus clouds are characterized by thin, wisplike strands, often accompanied by tufts, leading to their common (non-standard) name of mare's tail. Many cirrus clouds produce hair like filaments made of the heavier ice crystals that precipitate from them. These "fall streaks", a form of virga, often indicate the difference in the motion of air (wind shear) between the upper part of the cirrus cloud and the air below it. Sometimes the top of the cirrus cloud is moving rapidly above a slower layer of air, or the streak is falling into a faster moving lower layer. The directions of these winds can also vary.>>

[Chris Peterson]

Outside of the ultra dry southwest, virga almost always refers to SNOW that doesn't reach the ground.

Well, I live in the dry southwest. I've seen both rain and snow virga, but I do think the term is more generally used (everywhere) for rain. I also find that many people I talk to outside the west have never even heard the word.

We are certainly NOT looking at nearly total forward scatter here.
The Sun is due west-south-west while we are looking DOWN and to the northwest.

This is a quarter hour before sunset on the equinox. The Sun's azimuth is 268°, and the camera azimuth is about 282°. That's a difference of only 14°. That said, I don't really think it's scatter. Simple reflection off of water droplets makes more sense.

I have seen this exact effect from the ground in obvious virga, so there's no doubt in my mind that this could be the same.

Was it rain virga or snow virga?

Always rain. I've never seen snow virga (or snowfall) between me and the Sun look anything other than gray. (Snowfall on sunny days isn't uncommon in my part of the Rockies.)

[BMAONE23]

Plus, snowfall in September is also rare even in Minnesota

[Skywatcher2]

The Sun is due west-south-west while we are looking DOWN and to the northwest.

To try to get things a bit more precise for everyone on the angles involved, the sun at that time of day on that date at that location would better be described as west-west-west-west-south-west.

For reference as to the camera direction, one easily identifiable road that runs exactly east-west is the road that runs alongside the barn area (near the bottom right of the photo) to the southwest end of the training track. I think the photographer's description as "north of west" is somewhat more accurate than saying "northwest".

[neufer]

Outside of the ultra dry southwest, virga almost always refers to SNOW that doesn't reach the ground.

Well, I live in the dry southwest. I've seen both rain and snow virga, but I do think the term is more generally used (everywhere) for rain.
I also find that many people I talk to outside the west have never even heard the word.

Well, I worked at NOAA's World Weather Building in Camp Springs, Md., for about 30 years
and I can't remember anyone there use virga for anything other than snow.
(I'm sure the same is true for Minnesota.)

We are certainly NOT looking at nearly total forward scatter here.
The Sun is due west-south-west while we are looking DOWN and to the northwest.

This is a quarter hour before sunset on the equinox.
The Sun's azimuth is 268°, and the camera azimuth is about 282°.
That's a difference of only 14°. That said, I don't really think it's scatter.
Simple reflection off of water droplets makes more sense.

The camera is looking DOWN at more than 14°.

That said, the sun appears pretty darn small when reflected off of a sphere:

I have seen this exact effect from the ground in obvious virga, so there's no doubt in my mind that this could be the same.

Was it rain virga or snow virga?

Always rain. I've never seen snow virga (or snowfall) between me and the Sun look anything other than gray.
(Snowfall on sunny days isn't uncommon in my part of the Rockies.)

If you see sunlit gray virga in some other direction it is rain virga:

[BMAONE23]

(snip)
If you see sunlit gray virga in some other direction it is rain virga:

Is it just me or does that vortex have straight hexagonal sides like polar saturn

[neufer]

Is it just me or does that vortex have straight hexagonal sides like polar saturn

There's a hex on that town.

[Skywatcher2]

This is a quarter hour before sunset on the equinox.

Not that its relevant on the conclusions you're drawing, but just as another point of reference for everyone, TheSky6 says the sun set at 7:08 PM Minneapolis local time on 09/23/02. That would be within a minute of the time of the picture, not fifteen minutes.... assuming the camera's clock was accurate except for the time zone difference from where it was set.

[apodman]

TheSky6 says the sun set at 7:08 PM Minneapolis local time on 09/23/02. That would be within a minute of the time of the picture, not fifteen minutes.

Some adjustment to the sunset time, I don't know how much, needs to be made for altitude.

[geckzilla]

I've NOT neglected refraction or internal reflection... nor have these APOD's:
http://antwrp.gsfc.nasa.gov/apod/ap070912.html
http://antwrp.gsfc.nasa.gov/apod/ap060702.html

Are you trying to use these photos to say that rain droplets can't be colored (yes, oversimplification, hopefully you know what I mean) orange by the sun? I'm confused.

[Chris Peterson]

The camera is looking DOWN at more than 14°.

Maybe, but what matters if forward scatter is involved is the angle between the clouds and Sun, and that's quite small.

That said, the sun appears pretty darn small when reflected off of a sphere

But we're talking here about the reflections off of billions of spheres. And of course, the illuminated area is still only a fraction as bright as the Sun itself.