Category Archives: Seasons
As we head into the second half of August the days are noticeably shorter. That change is even more dramatic in the polar regions where the summer ice melt season is nearing its end.
This year’s melt has been particularly dramatic, with the Arctic sea-ice extent likely heading to its lowest level since satellite measurements began in 1979. The previous low extent record was set in 2012. Continue reading
With astrological summer set to begin on Friday morning at 10:54 a.m., it seems like a good time to consider the nature of this seemingly dreary and cold spring that we have just endured.
Almost no one will disagree that this year has had a memorably bad spring, not only locally but around the nation as widespread flooding has put elements of the agricultural sector well behind their normal schedules. Continue reading
Given our recent weather, and with the pollen season dawning in southern Wisconsin, one may wonder if there actually is a windiest time of year in Madison.
Of course, a windy day can come along just about any time of year (the record gust of 83 mph in Madison occurred in June 1975) but the climatology suggests that March and April are the windiest months of the year with average wind speeds of 11.3 and 11.4 mph, respectively. November through February are not far behind, logging a four-month average of 10.5 mph. Continue reading
Last year’s 7 inches of snow on April 18 provided vivid evidence that, though early April often brings the first string of nice spring days to southern Wisconsin, we are not truly out of the woods until the end of the month.
Despite the possibility of such an outlier event, recent research at UW-Madison has considered the variability of the end of winter based purely on temperatures above the surface. Continue reading
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