Venus atmosphere light refraction

[Richy]

Recently, I was in orbit around Venus, and watched many sunrises and sunsets. But I wondered about the color of the sun, respectively of the dawn and the color of the light thrown at my ship.
It was redish like on earth, but earth's atmosphere is blue, and so on absorbs the shorter wavelenghts make a sunset look red.

Would this way Venus brown-yellowish atmosphere absorb longer wavelenghts of light, and let a ship in orbit, passing the solar terminator appear in a blueish light? Or what else would it look like?

thx
Richy

 

[lennartsmit]

The orange colour means that orange/red is reflected by the atmosphere and that other wavelengths get through. You should see a blueish/violet sun, I think.

 

[cjp]

No, the atmosphere probably looks yellowish because small particles in it absorb blue light and reflect the rest. Otherwise, the sky would look blueish from the surface.

I think that when it comes to scattering of light due to gas molecules, blue scatters more than red, both on Venus and on Earth. So, the color of the Venus atmosphere above the clouds should be very similar to that on earth. Below that, there is a thick layer of clouds with a dirty yellow color. Once the sun sets below that, it is completely gone. The in-orbit view of sunrise/sunset colors is probably dominated by the atmosphere above the clouds. So I think Orbiter is correct.

 

[T.Neo]

Correct.

While both atmospheres scatter blue light, the Venusian sky (clouds removed) would probably appear a beige or cream colour from the surface, due to the higher atmospheric pressure.

 

[Bj]

Correct.

While both atmospheres scatter blue light, the Venusian sky would probably appear a beige or cream colour from the surface, due to the higher atmospheric pressure.

Hard to find a true color picture of Venus surface but this is as close as I can get.

http://en.wikipedia.org/wiki/File:Venus-venera13-right.jpg

oh wait, here's more

http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-venus.html

 

[Piper]

This is a good place for true color photos of Venus:

http://www.mentallandscape.com/C_CatalogVenus.htm

 

[T.Neo]

Hard to find a true color picture of Venus surface but this is as close as I can get.

I meant it would be that colour without the clouds. Fixed my post to reflect that.

The clouds make the sky look orangish-yellow on the surface.

 

[martins]

Hard to find a true color picture of Venus surface but this is as close as I can get.

http://en.wikipedia.org/wiki/File:Venus-venera13-right.jpg

oh wait, here's more

http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-venus.html

Interesting. According to the NASA site, these two images are the colour versions of the left and right half of a single original image. The colour balance of the two is quite different, one being very red, the other significantly more blue. It illustrates the problem of getting unbiased colour information quite impressively if you can't even get a consistent colour for a single image.
The original image (also on that site) seems black and white (although the caption says that a colour TV camera was on board). How was the colour information for the above images derived? Was this done by mapping low-res TV footage to high-res b/w images? And if so, how was the colour footage calibrated?

 

[TSPenguin]

From the site Piper posted:

The Venera landers transmitted digital images with a depth of 9 bits and an approximately logarithmic encoding of photometric brightness. Multiple panoramas were scanned by the camera, including some with red, green or blue glass filters in place. [...] An accurate conversion of that encoding to linear brightness has been derived, using calibration information included with the images.

That arm, visible in the first picture, seems to have color patches for calibration too.

 

[4throck]

Please read http://www.mentallandscape.com/C_CatalogVenus.htm
There's a detailed explanation of the color data available and modern image processing applied to the images, including sky spectra from diferent altitudes. Those can be usefull for correcting Orbiter's atmospheric appearance.