You say "It all melts", and then "I trust that the experts know the difference between permanent snow....".
I hypothesised satellite photos, I'm not sure if depth of snow is relevant for more than just volume, and whether you could get good estimates of depth (and density???) from a satellite.
Good to know. I have very little experience with snow itself.
I figured it would be lighter due to all the things people said, but had no rule of thumb to go on. And I try to go by the principle of being wrong in the best way possible. And since I wasn't aware of the density difference, I figured it would be safest to ignore it. Because people kind of forget how fast water gets heavy.
You could use it as a prompt to start doing more research to see if there actually is less snow. I'm not sure what else you could do with that information though, a tool for raising awareness of climate change?
Photos are better, they're useful for things like measuring glacier retreat. But even in your example there would be issues, if snow becomes noteworthy more people will take photos of it, so already you can only be confident of looking at the most extreme examples.
I don't think a camera would be good enough. You need to be able to investigate the layers involved. Maybe some kind of probe that measures temperature/composition as it penetrates the snowpack. And then take regular sampling along a ridge, etc. I suppose if you were to spend a lot of money you could have a drone drop the probe, too. Or maybe there's some kind of radar or whatnot that could penetrate the snowpack and measure density layers and so on.
The temperatures given are usually air temperatures. If the ground is warm enough -- which it is usually is in the cities -- then it doesn't really matter, the snow will melt in both cases.
Correct, but this is more about the slow accumulation of snow, not all of which melts during summer. Over thousands of years, this leads to thousands of feet of packed snow.
I'm sorry I don't have a figure for you, but it doesn't have to be very thick. As the snow starts melting, the grime actually concentrates and becomes darker.
When the sand falls on the snow in the Alps, it increases the ability of the snow to absorb heat from the sun (because it's darker -- this is known as "albedo") which accelerates the melting of the snow. This happens in the Western United States too, and has been studied [0] as a source of uncertainty in predicting snow melt timing (e.g. for things like water availability).
There's also the fact that predicting amount of snow is particularly difficult because the same amount of water will yield vastly different snowfalls with single-degree deviations of the temperature.
You say "It all melts", and then "I trust that the experts know the difference between permanent snow....".
I hypothesised satellite photos, I'm not sure if depth of snow is relevant for more than just volume, and whether you could get good estimates of depth (and density???) from a satellite.
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