Interesting image; what's making the shadow?

[owlice]

APOD received the following image and information with a request for an explanation; I got permission to post this here for your input.

[attachment=0]Mt Vernon_0075.jpg[/attachment]

I have attached a photo I took from the front porch at a winter sunrise. This hill is not that high so I cannot see that is really causing the shadow. The Cascade Mountain Range is to the south which are large enough to cast a shadow. However I cannot understand why it came from the peak of this small hill. (I don't know the height but it is an easy hour walk from the base to the summit.) I haven't seen it again.

In our email exchange, he said the sun was not yet visible but would rise later to the right.

I think a cloud is casting the shadow, but the cloud is not visible, either, because it's hidden behind the hill; the shadow is projected up onto the atmosphere/cloud bank.

What do you think? Is that a reasonable explanation, or is something else going on?

[Sam]

I'm pretty sure that it's a shadow from another cloud out to the right and the line just happens to line up with the summit; taking the picture from another 20 meters to the right or left would create a noticeable parallax.

Rays like this can be quite impressive, especially when they reaches all the way across the sky:

That the shadow doesn't repeat itself in the days following (which have a different cloud configuration) supports my point...unless on the same date next year the alignment is perfect again: http://asterisk.apod.com/viewtopic.php? ... 25#p137836

--
Sam

[Beyond]

I don't see any shadow. I see unlit clouds and lightend clouds that happen to be divided where the peak of the hill is, from that angle.

[Chris Peterson]

I don't see any shadow. I see unlit clouds and lightend clouds that happen to be divided where the peak of the hill is, from that angle.

The unlit clouds are being shadowed by something, aren't they? Otherwise they'd be lit as well!

As noted, we're just seeing a shadow cast onto those clouds by something between the clouds and Sun- possibly a hill, but most likely more clouds. It's just the coincidental angle of the shadow edge with the slope of the hill that produces the peculiar effect of the hill actually casting the shadow.

[owlice]

Thanks to all!