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dug up some post of conversations I had on the topic and wanted to add to it and thought they deserve their own thread. Hopefully whenever has something to post on a frost hollow, they could use this thread and bump it up. Don't think we have any threads on them other than some rate the climates of frost hollows. Any local frost hollows near you? Or somewhere else that interest you.
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Local topography is important at how potent a frost hollow is. Both in the Adirondacks and White Mountains, the coldest non-high elevation temperatures are found at locations that have favorable topography.
Quote:
Originally Posted by Rozenn
Narrow valleys surrounded by very steep mountainsides wouldn't work as well as flat one with more gentle terrain, other factors being equal. The portion of visible sky will be less and more infrared will be re-radiated towards the ground instead of just being lost in space. Drainage area would be an important factor. Are there closed frost hollows in the Northeast? I assume there are no limestone soils, so no (limestone allows for water infiltration into the ground, creating depressions).
Quote:
Originally Posted by nei
It's the champion frost hollow of northern New York / Northern New England. Compare with Pinkham Notch, in a deep valley surrounded by tall mountains (Mt. Washington to the west, peaks around 4400-4800 feet to the east) and 500 feet higher. Saranac Lake has colder nights. Not sure if that region of the Adirondacks are naturally chillier (or rather have a higher diurnal range from being more continental) or it's local topography. Would have thought a deep narrow valley would be the best for radiational cooling with cold air descending to the valley bottom. But maybe a wider valley would be better because there's more landmass to cool?
I had checked the stats of Whitefield, New Hampshire recently. It's on the edges of the White Mountains in a wide, flat-ish valley at 1000 feet or so. Pinkham Notch is at 2000 feet in a narrow V-shaped valley surrounded by tall mountains. While Pinkham Notch has warmer lows than Saranac Lake, Whitefield is almost as cold. Whitefield isn't far from Pinkham Notch, the terrain must make it have colder nights. So the less rugged local topography creates cold temperatures
I passed by the weather station cross-country skiing from the nearby French town of Les Rousses (that's how I found out about the Agrometeo website). Took a couple pics from the region. The frost hollow where the station is located is in the third photo:
Spoiler
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I once finished a skiing session late, around sunset. The temperature at the bottom of the valleys plunges fast once the sun sets and often a little while before. The difference between the ambient air (say, the house in the third pic) and the cold air pool at the bottom is striking. I find it fascinating.
Quote:
Originally Posted by nei
It even gets frosts in July, not just -0.1°C, but a -3.7°C! Elevation looks like it's around 13°C. Did the recent cold in eastern Europe affect any of the night temperatures there this month? Last winter had only one -30°C temperatures, still very cold and variable. Oh, whoops, found the elevation:
The Place who gets the coldest temperatures in Germany is Funtensee
Quote:
Originally Posted by Wikipedia
Known as the coldest spot in Germany, the lake is the site where the country's record lowest temperature, −45.9 °C (-50.6 °F), was recorded on 24 December 2001. It is theorised that due to the unique situation of trapped cold air, a temperature of -55 °C (-67 °F) is possible. The extreme cold spot at the lake is said to result in a reverse tree line, as no trees can grow at any point below about 60m above the lake, although studies have found that it was the result of overgrazing animals. Temperatures are regularly monitored by a private weather station installed by Jörg Kachelmann.
I have read an old paper which claims that a frost hollow outside Rickmansworth, Hertfordshire (to the Northwest of London) probably has the most continental climate of Britain. Elevation is 177 ft.
I have read an old paper which claims that a frost hollow outside Rickmansworth, Hertfordshire (to the Northwest of London) probably has the most continental climate of Britain. Elevation is 177 ft.
Another potent frost hollow in Switzerland would be the Glattalp. It's higher up and the thermometer measured -52.5°C (-63°F) there back in 1991. Checked the relief map, it's a closed frost hollow, which means cold air can't escape by gravity.
This page mentions a -34°C low last month, 10°C colder than Samedan that morning: Weather to ski
Problem is, as the article mentions, the location of the thermometer is apparently far from ideal. Would be nice to have a weather station up to the WMO standards there.
Quote:
Originally Posted by Donar
-2.5 °C average low in January is quite impressive, of course only 1930-1942 but I don't think that was a particular cold period?
The average low in January over that period in Paris was about the same as that of the 1951-1980 period. I assume the anomalies would be about the samein SE England. So yeah it was definitely colder than nowadays, but not really a freak 10-year period either.
Another potent frost hollow in Switzerland would be the Glattalp. It's higher up and the thermometer measured -52.5°C (-63°F) there back in 1991. Checked the relief map, it's a closed frost hollow, which means cold air can't escape by gravity.
This page mentions a -34°C low last month, 10°C colder than Samedan that morning: Weather to ski
I dunno, I haven't found a link to the history of that weather station. But I suppose negativ double digits are possible, at least in early June, given the temps recorded at the Combe des Amburnex at a significantly lower elevation.
Damn, all this talk about the abundance of frost hollows in the Juras makes me want to go there so badly. But, I have neither the time nor the energy, nor do I know how to get there, and even if I did I don't have the proper gear to just sit and camp there for hours at -30C in the middle of the night.
Anyways, the best region for frost hollows that I know of is the Utah sinks:
There's a sinkhole in northern Utah which is very effective at causing temperature inversions.
These temperature inversions are so pronounced that it can be -50C at the bottom of the valley while it's only -15C at the top of the valley.
It's responsible for the second-coldest temperature ever recorded in the contiguous US: -69F / -56C on Feb 1, 1985
Spoiler
Peter Sinks is a natural sinkhole in northern Utah that is one of the coldest places in the contiguous United States.
Peter Sinks is located 8,100 feet (2,500 m) above sea level, in the Bear River Mountains east of Logan, within the Wasatch-Cache National Forest. Due to temperature inversions that trap cold nocturnal air, it routinely produces the coldest temperatures in the state. Even in the summer, the bottom of the sinkhole rarely goes four consecutive days without freezing. It is so cold near the bottom of the hole that trees are unable to grow.
On 1 February 1985, a temperature of −69.3 °F (−56.3 °C) was recorded there, the lowest recorded temperature in Utah, and the second coldest temperature ever recorded in the continental United States.
Peter Sinks was discovered meteorologically by Utah State University student Zane Stephens in 1983. Stephens, along with the Utah Climate Center, placed measuring instruments in the valley in the winter of 1984. On February 1, 1985, Peter Sinks dropped to −69.3 °F (−56.3 °C), while another nearby valley, Middle Sink, located 3 miles to the north-east, dropped to −64 °F (−53 °C). Stephens hiked into Middle Sink to record the temperature personally. He then flew into Peter Sinks in a KUTV television station helicopter with broadcasting MeteorologistMark Eubank. State Climatologist Gayle Bingham also traveled to the area and confirmed the temperature. The alcohol thermometer being used was retrieved and sent to the Bureau of Standards in Washington, D.C. to confirm the temperature.
Since 1985, Peter Sinks and Middle Sink have been studied extensively by Stephens and Tim Wright with the use of Campbell Scientific weather equipment. On January 29, 2002, the temperature dropped to −62 °F (−52 °C) at Middle Sink. Stephens and Wright's main study is the change in temperature through the inversion at these sites. The valleys act like a dam trapping cold air. The coldest of the air settles to the bottom of the valley. Stephens and Wright have found that temperatures between the cold air "lake" and the warmer air above the valley can be different by as much as 70°F (39°C).
Another area dense with frost hollows is the Adirondack Region in NY State. In fact, the regional airport there (KSLK) is located in one itself, and it has an average annual low of -31F (-35C). This region is also responsible for the lowest temperature ever recorded in the Eastern United States (east of Wisconsin, to be precise: https://en.wikipedia.org/wiki/U.S._s...ature_extremes), which was a -52F (-47C) in Old Forge. Absolutely beautiful place btw.
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