Category Archives: Seasons

When is spring?

The seasons result from the tilt of the Earth and its yearly circling of the Sun. According to the astronomical definition, spring occurs when the Sun’s rays strike the equator at noon at an angle that is directly overhead. This particular time varies from year to year due to variations in the Earth’s orbit about the Sun. In the Northern Hemisphere the Vernal (or spring) Equinox (equi, ‘equal,’ and nox, ‘night’) occurs sometime between March 19 and 23, but often on March 20 or 21. This year astronomical spring arrives on March 20 at around 4:58 P.M. CDT. During the equinoxes all locations on Earth experience 12 hours of daylight and 12 hours of darkness. The Sun rises due East and sets due West. Equinoxes are the only two times a year that Sun only rises due east and sets due west for every location on Earth! After the Spring equinox, the Northern Hemisphere tilts toward the Sun, and we start to get longer, sunnier days.

Spring marks the transition from winter to summer. Meteorologists divide the year into quarters to compare seasonal and monthly statistics from one year to the next. Meteorological spring is defined as March through May and so begins on March 1. We might also define spring as the day on which, if there is precipitation, it is more likely to be in the form of rain than snow. For southern Wisconsin, that occurs later in the month of March. Continue reading

Category: Climate, Seasons

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Why is ice different colors?

Some ice is called “black ice,” which refers to one of two conditions: A new layer of clear 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 of these cases, the ice is not actually black but is transparent and therefore shows the color of the underlying surface. Continue reading

Category: Seasons, Weather Dangers

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Is there energy in snow?

Since the beginning of this year, Madison and Dane County have received about 35 inches of snow.

Snow is a form of solid water and water is the only substance that occurs naturally in all three phases — solid, liquid and invisible gas — in the Earth’s atmosphere. Of course, that means that the 35 inches of snow began as the equivalent amount of water in the invisible vapor (gas) phase before it was transformed into solid water. Continue reading

Category: Meteorology, Seasons

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How good are the groundhog predictions?

The predictions made by this folk forecast are correct only about 40 percent of the time — vastly inferior to what is delivered by modern science. If you flip a coin, you’ll be right close to 50 percent of the time.

This year’s prediction by the furry animal is for an early spring. As for a more scientific approach, temperatures over the next six weeks look about average. Continue reading

Category: Meteorology, Seasons

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How low will temperature go?

On Jan. 30, 1951, the morning low temperature in Madison fell to minus 37. Nearly 12 years later, on Jan. 15, 1963, the mercury dropped to precisely minus 30.

These two days remain the only dates in Madison’s recorded history with temperatures as cold as minus 30. On those record-setting days a number of characteristic meteorological conditions were in play to drive the temperature to such extremes. Continue reading

Category: Meteorology, Seasons, Severe Weather

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