APOD: A Strange Sunrise Over Argentina (2011 Oct 10)

[Ann]

OrionEridanus wrote:
@Ann. The cloud demonstrates curvature because you don't generally see a cumulus cloud with its base right at see level. The unclouded air gap between the cloud base and the ocean surface (and maybe the cloud base itself) are below the horizon.

Thanks! Yes, that makes sense!

Ann

[alter-ego]

Do you mean that if we keep watching this sunrise and "cloudrise", we will either see the clouds "leave the horizon", or else we will see more and more of the large cloud appear from below the horizon?

Yes. That could be the case, or prevailing winds could drive the cloud below the horizon. I guess I was picturing that cloud being brightly illuminated just before actual sunrise (in the sun's soon-to-be location) being first to usher in the new day.

[Strangerbarry]

I think it is the inhabitants of the Falkland Islands conducting a test nuclear explosion as a sublty veiled warning to the Argintines not to re-invade

[islader2]

@ STRAGERBERRY Your comment is purely political and insulting to Argentinians==Luigi included. You should include a disclaimer {IMHO} since we oldtimers and solons try to steer away from gratuitous insults. Such a great picture! and you resort to such baseness.

[epitalon1]

Hi,

this topic makes me think about another: the size of full moon when it rises.
APOD editor frequently states that there is no obvious explanation, nor any obvious measurement or proof of it.

I am just wondering : could it be that, when full moon rises, there is a superior mirage taking place, that would enlarge the moon image.
It would make it appear slightly above its actual position, but the offset would have been unnoticed until now ?

Full moon rises just after sunset, when upper layers of the atmosphere are just kept warm by the setting sun while lower layers are in the dark.
What about this idea ?

[geckzilla]

epitalon, I don't think there was ever a debate that the moon illusion is, in fact, an illusion. There are definitely ways of measuring it and people have done so. The question is what causes our minds to be fooled into it. Quote from this APOD:

The historically most popular explanation then holds that the mind interprets more distant objects as wider, while a more recent explanation adds that the distance illusion may actually make the eye focus differently. Either way, the angular diameter of the Moon is always about 0.5 degrees.

[neptunium]

I think what we are seeing here is a combination of a fata morgana and an inferior mirage. The clouds that are seemingly above the horizon when they are actuslly below it is the inferior mirage while the heavily distorted view of the sun is the fata morgana. It is amazing how much a fata morgana can distort an object.

And epitalon1, I see what you are getting at, although it has nothing to do with a superior mirage. When at or close to the horizon, the sun and moon appear to be a different color and are enlarged. I don't know what that effect is called, if it even has a name. However, this is NOT a superior mirage.

Instead, a superior mirage is caused when light refracts off colder, denser air than the air that is immediately below it. This causes the image to become inverted and appear to be upside-down. A fata morgana, on the other hand, occurs when light is bounced around and refracted in many different ways. The object seen therefore may appear to be upside-down, up in the air, flipped around, irregularly proportioned, or a combination of these effects.

For more information, click on this link:
http://en.wikipedia.org/wiki/Mirage

[neptunium]

The coloration of the sun and moon may also be caused by the sun and moon, too.

[neptunium]

Whoops! I meant to say horizon haze, not sun and moon!

[tims]

I use APOD pix for my screen saver. By coincidence the picture of the strange sunrise in Argentina is followed by one of a solar flare. I am struck by the similarity in the shapes. I wonder if there is any possibility that the atmosphere functions as a magnifier of a solar flare occurring at the time the picture was taken. I guess one could find out exactly when the picture was taken and then check to see if there were any significant solar flares at the time.