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lisab said:
t I'll take a pathetic stab at this...

That's what I decided against first :smile:

are the conditions that cause ground fog different from the conditions that cause the poofy clouds above the fog?

My other bet is that there is a little bit of wind (see smoke/condensation over some houses chimneys) which should move the fog. But it is as pathetic as "poofy clouds" :smile:
 
Physics news on Phys.org
Ever seen poofy clouds and ground fog in the same picture?

groundfog.jpg


What are those poofy clouds?

cumulus: a low cloud that develops from the bottom up. Appear white and puffy, with a cauliflower-like top. Small ones are associated with fair weather(cumulus humilis), but as they grow vertically, they can produce rain showers (cumulus congestus).

Cumulus are typical for a nice sunny day when the convection takes water vapor up, the rising air cools adiabatically and condensation takes place, revealing the typical circular turbulent motions of the convecting air. However when the sun sets, the convection stops and the clouds dissipate. No small cumulus in the night, let alone in the early morning, the big storms yes, but these don't qualify. Also cumulus is associated with cold fronts moving in; the cold air forcing the warmer air in front, upwards giving the same effect. But those fronts are also associated with moderate winds, which are not there, since the ground fog could not have existed.

So no cold front and no fair weather convection, so this seems an impossible situation, if it wasn't for a third explanation.

Anybody?
 
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We are left with a warm front...

But it is as pathetic as all previous trials.

Edit: nah, wiki doesn't state anything about cumulus being present at warm fronts.
 
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Borek said:
We are left with a warm front...

But it is as pathetic as all previous trials.

Edit: nah, wiki doesn't state anything about cumulus being present at warm fronts.

Nah indeed, warm fronts are associated with stable air without convection, layered clouds only.

Think topography.
 
Andre said:
Nah indeed, warm fronts are associated with stable air without convection, layered clouds only.

Think topography.

Is there a body of water under the fog?
 
lisab said:
Is there a body of water under the fog?

Jackpot, that is almost. Lisa :approve: It's under the Cumulus clouds, not under the fog.

It's the North Sea being about 10 degrees warmer than the atmosphere. That would get the convection going.
 
It's a very nice picture Andre, too bad I was too late to the guessing game.

I was going to say you photomerged them in :-p
 
Thanks Christina, I was actually waiting for that one.
 
Turbo, Borek, the comprehensive review of the 50D is published on DPreview.

http://www.dpreview.com/reviews/canoneos50d/

It's somewhat of a disappointment. Image quality suffers from too many pixels.

Compare for instance the RAW image quality of the 450D at just over one third of the price of the 50D:

http://www.dpreview.com/reviews/canoneos50d/page25.asp
http://www.dpreview.com/reviews/canoneos450d/page31.asp

The 450D is clearly better at high ISO:

http://www.dpreview.com/reviews/canoneos50d/page29.asp
http://www.dpreview.com/reviews/canoneos450d/page32.asp

So I would not put the 50D on my short list for a possible upgrade for now.

Note that the only camera's that share with the 450D a image quality score of "9" or better, are many times more expensive:

http://www.dpreview.com/reviews/nikond700/page32.asp
http://www.dpreview.com/reviews/canoneos1dsmarkiii/page32.asp
http://www.dpreview.com/reviews/nikond3/page34.asp
http://www.dpreview.com/reviews/nikond300/page32.asp

Edit: update. This is how the 450D performs for image quality with the kit lens (in RAW).

smilespiderdetail.JPG


It's the smiling spiderweb picture in full frame at 10% size. I had to move out quite a bit to get some depth of field since there was considerable distance between the webs. The crops from the red squares are at 100%.
 
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Ooh, boy, I got to play with a really NICE camera today! Our department has a camera for us to use for photos for illustrations, such as for textbooks, and I got my first lesson on using it today. I'm very tempted to work all weekend, just to take time playing with the camera to get more familiar with it. Got some wonderful photos...it's so much easier with a great camera! And NOW I know how larkspur gets some of her amazing photos...the camera has a macro lens for it, and I got some really nifty photos using it.

The only downside at the moment is that they're all anatomy photos, so I can't share here...I REALLY want to be able to show off one of them that is both technical and still artistic. I think I'm going to make it my wallpaper on my work computer. :biggrin:
 
Can't speak about others, but - personally - I am not afraid of anatomy pictures.

anatomy.jpg
 
Moonbear said:
Ooh, boy, I got to play with a really NICE camera today! Our department has a camera for us to use for photos for illustrations, such as for textbooks, and I got my first lesson on using it today. I'm very tempted to work all weekend, just to take time playing with the camera to get more familiar with it. Got some wonderful photos...it's so much easier with a great camera! And NOW I know how larkspur gets some of her amazing photos...the camera has a macro lens for it, and I got some really nifty photos using it.

The only downside at the moment is that they're all anatomy photos, so I can't share here...I REALLY want to be able to show off one of them that is both technical and still artistic. I think I'm going to make it my wallpaper on my work computer. :biggrin:


Have fun Moonbear. Can't wait to see some of your shots. You live in a beautiful area an can get some awesome landscapes.
 
Moonbear said:
the camera has a macro lens for it,

I miss my macro lens! :cry: My <prized> macro was stolen, my normal lens was just broken, my big telephoto doesn't seem to be working, ..... all I am left with is my small telephoto. Which is :zzz: my most boring lens.

edit: Borek= it took me two times to figure out your picture. Too funny! (I'm a little slow today)
 
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ahahahaha! Nice, Borek.
 
Considering I so badly want a really wide angle lens, I don't know why it took my so long to try simulating the effect by stitching shots together. This is two shots stitched vertically in Arcsoft Panorama Maker.

3049404473_ee4cc8b42e.jpg


I also used some ND grad filters to darken the window, as it was too bright compared to the foreground.
 
Nice job with the exposure Matthyaouw.
 
Well, winter is here. The gusty (30-40 mph) winds seem to come from every possible direction, as you can see from the way the snow is scattered on the pond below my back deck. I didn't embed the image because it is very wide and would have caused browser windows to resize. 4 images (with lots of overlap) stitched with the Canon utility.

http://i183.photobucket.com/albums/x318/turbo-1/smallstitched.jpg
 
turbo-1 said:
Well, winter is here. The gusty (30-40 mph) winds seem to come from every possible direction, as you can see from the way the snow is scattered on the pond below my back deck. I didn't embed the image because it is very wide and would have caused browser windows to resize. 4 images (with lots of overlap) stitched with the Canon utility.

http://i183.photobucket.com/albums/x318/turbo-1/smallstitched.jpg

Nice pond! Is the ice thick enough to skate on yet?
 
larkspur said:
Nice pond! Is the ice thick enough to skate on yet?
Not yet. The pond looks very small in this picture, but for scale the larger rock at the upper right is over 3' wide. I need to do some landscaping out there when money permits. The pond is fed with groundwater and it's deep enough not to freeze solid, so the fish I threw in there when we moved in are still thriving.
 
It looks interesting turbo.

I like that black and white picture from
but I don't use filters..I would like to but they cost a lot.

I really want a neutral density filter so I can take a slow shutterspeed shot in the daytime. (very pretty water effects)
But..it's a whole lot of money.
 
Filters are fun. I have an ND4 and an ND 64, but combined they aren't quite up to the job of long exposures in strong daylight (not helped by my smallest aperture being f8). I have an infrared filter too, which I can get some pretty long exposures out of in most conditions:

2876350194_b80cbaf063.jpg


I would absolutely love one of those 10-stop NDs some time, but you're right they are pricey.
 
Look at the ghost of a man leaning toward the pole with his arm bent and reaching for the pole. :bugeye:
 
Evo said:
Look at the ghost of a man leaning toward the pole with his arm bent and reaching for the pole. :bugeye:

I see it!
 
The exposure was 10 seconds, and i think he wandered on pretty late in it. Compare to here where he didn't move an inch. Can't say fishing is strenuous, can you? :biggrin:
 
Opening the curtains this morning to see this:

25ppely.jpg
 
Thanks, actually the Bonsai (Ulmus parviflora) needs some grooming badly, but I had a crazy season, everything at the same time. So it has to wait until springtime for the great make over
 

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