Talk:Sun dog

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1 Little Extra Explanation
2 Comment
3 One word or two?
4 Usage
5 Aesthetic image added

[edit] Little Extra Explanation

Snow is ice (if you compress snow without melting it will compact to ice as occurs often at the bottom part of a snow pack towards the end of winter), and super cooled water droplets do not necessarily turn to ice at 0 C. Since they are so small the probability of nucleation occuring in the droplet is also small so that they usually remain liquid well below freezing. Nearly pure bulk water freezes at around 0 C because a single nucleation event is highly probable somewhere in the water. Once there is an ice nuclei, it starts a domino effect where nearby water molecules accumulate around it and so on until the entire thing is frozen. You can prevent freezing in bulk water at 32 C by keeping the water in motion which often occurs in waterfalls and rapidly moving streams. For them to freeze the temperature usually has to be well below 15 F for quite a while.

I think the reason sundogs are more commonly seen during winter is because the sun sets earlier, it spends more time near the horizon (which is needed to see a sundog), skies tend to be less cloudy and hazy across large chunks of North America and Asia, and cirrus occur at lower levels, so they are more likely to be seen in front of a setting sun.

In light of this, I think that the page should be updated so that it does not claim that sundogs are winter phenomena.

[edit] Comment

"it is only produced in clouds cold enough to be ice rather than water, which only occurs far below 0°C."

I'm a little confused, there is no water below zero degrees. Water freezes (and turns to snow) at zero degrees, not far below. In fact most clouds that high are frozen, even in summer. Perhaps the author meant "cold enough to be ice rather than snow".

At any rate, Personal observations tells me that sun dogs only appear on very cold days.

(William M. Connolley 09:51, 24 Feb 2005 (UTC)) Water clouds will remain super-cooled down to quite low temperatures. Absolutely pure water droplets won't spontaneously freeze until it gets to something like -40 oC (I forget the exact number). Air containsCCNs so I think water droplets in the atmos tend to freeze at about -20 oC ish.

Almost correct: It's not CCNs (cloud condensation nuclei) that cause supercooled droplets to freeze, but rather so-called ice nuclei (IN), which can trigger ice formation at various temperatures depending on particle composition, size, etc. Usually IN won't cause a cloud to fully glaciate; therefore pure ice (cirriform) clouds are usually found only at temperatures colder than -40. Sundogs may occur in any weather, any season, as long at the clouds contain ice particles of the right shape. Note also that sundog is spelled as one word by most meteorologists. - Grant Petty

[edit] One word or two?

Is it sun dog or sundog? The title uses one form, the first sentence the other. Should be consistent. If both forms are correct, the first sentence should give both, with the first form matching the article's title: e.g. " A sun dog (or sundog) is a relatively common...." — Franey 12:46, 24 August 2005 (UTC)

m-w.com gives 'sun dog', AHD gives 'sundog'; 'sundog' outnumbers 'sun dog' on Google. There is probably no standard form, so both could be "correct" (really though, "correct" is POV applied to English spelling: there are no regulating bodies, only established usage).

Ideally the same form would be used throughout the article—and it is, apparently; unfortunately it is not the form used in the title. —Muke Tever talk (la.wiktionary) 01:29, 25 August 2005 (UTC)

[edit] Usage

Does anyone know how widely the word "sun dog" is used, less or more so than parhelion? I've not heard of either term, so I don't know if it's common in Britain, but it does sound like an Americanism. Any ideas on this, and also where & why the term originated? --User talk:El Pollo Diablo|Talk 01:38, 26 November 2005 (UTC)

I say "sun dog" and I'm British. Parhelion is more technical. William M. Connolley 21:10, 6 December 2005 (UTC)

The term (sundog) is used in Canada. Hu Gadarn

'Sundog' doesn't quite capture the beauty of what's happening, I wish there was a nicer name for it. So I use parhelion —The preceding unsigned comment was added by Drumnbach (talk • contribs).