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Distribution of days here in January/February by mean temperature. Graph is relative frequency of each temperature. Blue line is all days. Orange line only the days it snowed at least one inch.
Snowy days are more concentrated in the 20s. But colder temperatures occur about as often on a snowy day as on any day in January / February. Another graph of the same data. Probability it snows at a given daily mean temperature. Constant in the 20s, unsurprising drop off above 30°F. Below around 17°F snow becomes less common, until it goes back up (rather spiky, not enough data points at very cold temperatures). I checked a couple of those very cold snowy days. One had a daily max of 23°F, min of -14°F. Snow was accompanied by a cold front, with a sharp drop in temperatures. Others had similarly very cold night. Hard to say if the increase at the cold temperatures is meaningful as there's not much of a sample.
Am I the only one who is frequently irritated when people talk about weather and they come up with totally exaggerated statements or huge misconceptions?
What are the most frequent ones in your country/relatives/friends?
For me, in no particular order :
"It's always cold in Canada/Russia/Alaska" (depending on people) Sorry, but each of these areas, except for their northernmost part, have warm summers, even Siberia (Yakustk, 25°C!) and Alaska (Fairbanks, 23°C)
Warm summers? Not really true for much of Alaska or Russia. Coastal areas have cool summers. Well, I guess it depends on what you call warm. Warm enough for me, but tourists are usually bundled up with parkas and gloves. Average highs in left column and lows in right column for Juneau, Ak.
62 48 June
63 51 July
63 50 August
57 46 September
It's more than a little entertaining when the weather is a bone of contention.
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Originally Posted by nei
Hard to say if the increase at the cold temperatures is meaningful as there's not much of a sample.
Not when you use global data, it's very easy to show that snow is always associated with cold temperatures, never the reverse. Let's not forget my objection, or the misconception involved here.
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Originally Posted by SFX
Most annoying (and wrong) climate claim?
"It snows more because it's warmer"
That is an absurd claim, it goes against physics.
Quote:
Originally Posted by alex985
Uh, yeah you are making a claim (of which you have no statistical data to back it up).
All the data, reality itself "backs it up", while the claim "it snows more when it's warmer" has no actual data to support it.
Quote:
Originally Posted by nei
Huh? You lost me there. Why should a warmer than average winter lead to less snow if it's still below freezing?
It's not about entire seasons, though the same pattern shows up even then. It's about heavy snow events, or even a heavy seasonal amount of snow. Where it's warmer than average, there is never more snow. That is the exact opposite of what we know actually happens, in the real world around us.
Quote:
Originally Posted by Shalop
What you are saying is blatantly and demonstrably false.
See? I am saying that the claim "It snows more because it's warmer" is nonsense. But now somehow it's "my claim", and some people are now defending the very idea that it snows more when it's warmer than average, rather than what reality shows.
Quote:
Originally Posted by Shalop
It is true that in most cities in the continental US, colder winters are directly correlated with snowier ones, but as nei and others have pointed out this has less to do with "cold = snow" and more to do with borderline snow events where the temps are very close to freezing.
No, it is exactly because it's colder that there is more snow.
Quote:
Originally Posted by Shalop
In fact, if you look at data outside the continental US you will easily see that for general cold-winter climates, there is absolutely no correlation between colder temperatures and more snowfall.
Of course there is, the physics of this is true everywhere that temperature is the main factor for snow. Obviously, as I mentioned right away, this is not going to be true for polar deserts.
Quote:
Originally Posted by Shalop
For example, if you go to the Nowdata page for NWS Fairbanks, you will see that the coldest years and the snowiest years are not related:
That's a strawman, nobody is talking about annual data. However, even globally we can see that warm tears show up in the snow extent data. As a gneral rule, warmer means less snow.
Quote:
Originally Posted by Shalop
Similarly, if you check data for Siberian cities on PogodaKlimat, you will easily see that colder temperatures have nothing to to with more snow (in fact, it is quite the opposite: higher snowfall is correlated with a weaker Siberian High).
We have all agreed by now, that where there is always snow in the winter, temperature isn't as important. But that isn't the claim I objected to at all.
Quote:
Originally Posted by Shalop
Hence, your claim that "cold = snow" is just plain wrong, at least for climates well within the continental and subarctic zones.
It's about heavy snow events, or even a heavy seasonal amount of snow. Where it's warmer than average, there is never more snow. That is the exact opposite of what we know actually happens, in the real world around us.
In the real world, that is not true where there is usually snow in the winter. Check the Berlin, New Hampshire graph. Berlin, New Hampshire is far from subarctic; it's only 150 miles from Boston. At the same time, it also disagrees with Shalop and alex985; there's not a correlation of colder = less snow by monthly temperatures. My daily graph for Amherst shows a small decline in snow at cold temperatures and then an increase at the coldest, but that's muddled by using the daily mean.
Quote:
We have all agreed by now, that where there is always snow in the winter, temperature isn't as important. But that isn't the claim I objected to at all.
That is where the claim refers to, and that's where everyone disagreeing with you is talking about. If you were specific enough to refer to places where the winter isn't mostly snow covered, no one would disagree.
Here's a scatter plot of mean temperature and snowfall. At the higher temperatures (I've included December and March) heavy snow becomes less likely. But below about 27°F, the correlation becomes weaker. If I plotted a station 100 miles north of me, it'd be weaker.
If you plotted that using Tmin and then another with Tmax, my point would become obvious.
Of course it's not my point at all, it's what physics tells us happens.
And meteorology.
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A snow ratio, simply, is the amount of water you get after melting snow. The average snow ratio is 10:1, so if you take 10 inches of snow and melt it, you get 1 inch of water. That is typical. But, we often see snow ratios lower (around 5:1) or much higher (20:1). This will affect how many inches you see in your backyard!
When the atmosphere is much colder than "near zero", snow stays dry, and there is more of it.
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Dry snow or fluffy snow falls when all of the layers of the atmosphere are below freezing-as well as the surface. Because the air is cold, the snow does not melt as it falls, so the flakes stay small. The snow ratio for this kind of snow is more like 20:1 or 30:1. This kind of snow can be dangerous because you don’t need a huge storm to end up with a ton of snow, you only need a little.
The determining factor for "how much" snow falls, is temperature, all else being equal.
When it's near or just above freezing at the surface, wet snow falls, or a mix of snow and rain, and this wet snow is called "light snow", even when it's actually heavy flakes. The "fluffy snow", which is light dry snow, is what causes the "heavy snow", which is used to describe snow when there is a lot of it.
This is why it's annoying when people claim it snows more when it's warmer.
When the atmosphere is much colder than "near zero", snow stays dry, and there is more of it.
The determining factor for "how much" snow falls, is temperature, all else being equal.
Snow ratios depend on temps aloft. Optimal dendrite formation occurs when 850 mb temps are between -20 and -10C, so snow ratios will be highest when this occurs. When that happens, surface temps tend to be quite low themselves (teens or 20s), so the article dumbs it down and states blatantly that colder temps directly correlate to the highest ratios, which is mostly but not always true.
In any case, when average temps are extremely low (say <-20C), the total precip amount is so low that, despite high ratios, the total snowfall will still be generally lower than if average temps were more modest (-5C or so). This is easily seen in some of the links I posted earlier about Alaska or Siberia (which are outside of the so-called "arctic desert" you keep talking about). So, in this case, warmer temps are correlated with more snowfall.
Quote:
When it's near or just above freezing at the surface, wet snow falls, or a mix of snow and rain, and this wet snow are "light snow", even when it's actually heavy flakes. The "fluffy snow", which is light dry snow, is what causes the "heavy snow", which is used to describe snow when there is a lot of it.
No, you've got it mixed up. The words used to describe low-ratio snow that occurs at temps at or near freezing are "heavy," "wet," "cement-like," etc. The words to describe high-ratio snow that happens at lower temps are "light," "feathery," "fluffy," "powdery" etc.
You should be careful with your terminology. The words "light" and "heavy," as used by the NWS, are used to refer to the rate at which snow falls, as opposed to its consistency. Heavy snow refers to snowfall rates more than 1 inch per hour or so, whereas light snow refers to rates less than 0.1 inches per hour or so. So, there are double meanings to those words which may contradict each other depending on the context and situation.
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This is why it's annoying when people claim it snows more when it's warmer.
Like I pointed out earlier, that claim is quite correct for much of Canada, Alaska, Siberia, sub-Siberia, etc. So, you have no reason to be annoyed.
Below around 17°F snow becomes less common, until it goes back up (rather spiky, not enough data points at very cold temperatures). I checked a couple of those very cold snowy days. One had a daily max of 23°F, min of -14°F. Snow was accompanied by a cold front, with a sharp drop in temperatures. Others had similarly very cold night. Hard to say if the increase at the cold temperatures is meaningful as there's not much of a sample.
I think I see the problem at last. I'm not saying "it snows more often", which is a different issue. I am saying the colder the air, the more snow falls, from the same amount of precipitation. Or rather, I took issue with the claim "It snows more because it's warmer".
Quote:
Originally Posted by SFX
Most annoying (and wrong) climate claim?
"It snows more because it's warmer"
Quote:
Originally Posted by alex985
That's not wrong. Warmer air holds more moisture hence more precipitation. Certain places are cold enough that warmer-than-normal doesn't necessarily mean less snowfall.
Quote:
Originally Posted by SFX
Of course it is. It's so wrong, and so easy to prove, it's unbelievable that anyone would fall for such a blatantly false claim about something like this.
It's very annoying.
The amount of snow is greater when it's colder. (at which point somebody will wonder what "colder" means)
While the amount of precipitation (that is going to fall as snow) is a variable, all other things being equal, the amount of snow is directly connected to how cold the air is. It snows more when it's colder.
Not when it's warmer.
Which is the reason it's so annoying to hear somebody claim the opposite is true.
While the amount of precipitation (that is going to fall as snow) is a variable, all other things being equal, the amount of snow is directly connected to how cold the air is. It snows more when it's colder.
Not when it's warmer.
Which is the reason it's so annoying to hear somebody claim the opposite is true.
Nobody is talking about snow ratios when they make that claim; they are obviously talking about the seasonal snow total which is mostly dependent on the amount of precipitation that falls as snow.
The amount of snow is greater when it's colder. (at which point somebody will wonder what "colder" means)
While the amount of precipitation (that is going to fall as snow) is a variable, all other things being equal, the amount of snow is directly connected to how cold the air is. It snows more when it's colder.
Not when it's warmer.
Which is the reason it's so annoying to hear somebody claim the opposite is true.
Sure, the snow ratios go up with a decrease in temperature. But all other things don't stay equal; saturate warmer air holds more moisture, allowing faster precipitation rates. And depending on location, very cold air temperatures are associated with dry airmasses. Overall for New England, colder months are somewhat correlated with more snow; see the graphs. Though it's not that tight a correlation.
Nobody is talking about snow ratios when they make that claim; they are obviously talking about the seasonal snow total which is mostly dependent on the amount of precipitation that falls as snow.
No, obviously the claim is about temperature and snow being heavy.
Quote:
“Heavy snows mean the temperature is just below freezing, any cooler and the amount would be a lot less,” adds Kevin Trenberth, a climate expert at the National Center for Atmospheric Research.
That's completely wrong, and it's even more annoying because a Meteorologist would know better than to make that claim.
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