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Category Archives: Seasons
What is “black ice?”
The term “black ice” refers to one of two conditions: a new layer of ice on water, which appears dark in color because the ice is transparent and so we see the deep water below, or a layer of clear ice on a roadway, which makes for hazardous driving conditions.
In both cases the ice is not black, but transparent, and therefore shows the color of the underlying surface. Continue reading
When does the last deep-cold spell of the winter usually come?
As we all work to recover from our recent cold spell, the natural question is: Are we done with bitter cold for the winter?
If we use an overnight low temperature below zero as the definition of a cold spell, then 26 of the 45 winters since 1970-71 have seen a cold spell after Feb. 15 — that’s 64 percent of the time. In fact, in 1974, the last below-zero night was not until March 24, the latest date in the last 45 years. Continue reading
Category: Meteorology, Seasons
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What is Groundhog Day and do the forecasts work?
Long before computers, the Weather Channel and the Internet, humans needed weather forecasts. Farmers and sailors particularly needed to know if storms were approaching.
Over time, various folklore forecasts, often in the form of short rhymes, were devised and passed down through the generations. Although memorable, the folklore forecasts are of uneven quality—some good, others bad. Continue reading
Category: Climate, Meteorology, Seasons
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What’s really going on in that slush puddle?
The recent snow and ice followed by a bit of melting filled sidewalks and some city streets with puddles of slush — that wondrous winter concoction of liquid water and ice.
Though it is not possible to see, surrounding any puddle of slush is also a cloud of countless invisible water vapor molecules. In fact, of all the many chemical constituents of the Earth’s atmosphere, only the water substance can naturally occur in all three of its phases – solid, liquid and gas – at Earth temperatures. Continue reading
Is our December abnormally warm?
The mildness of the first half of December in southern Wisconsin has probably not escaped anyone’s attention.
Despite the first visit of relatively cold air we just experienced over the weekend, both Madison and Milwaukee have already recorded the second warmest first halves of December in their respective records. Through Dec. 16, Madison’s average temperature for the month was 39.7 degrees, a full 14.4 degrees above the average. Continue reading
