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Answers: When do the seasons begin By Jack Williams, USATODAY.com
Q: When does the Western Australia winter start and end? When does the Western Australia Summer start and end?
A: This question gives me a good reason to talk about the seasons in general, not only those in Australia. First, let's look at Australia and then to the seasons everywhere, especilly in the USA. Since Australia is in the Southern Hemisphere, the seasons are opposite to those in the Northern Hemisphere, which of course, includes the USA. This means that winter Down Under in Australia runs from June 1 through Aug. 31 and summer from Dec. 1 through Feb. 28 (29th in leap years). This is true of all of Australia, including Western Australia. While you often hear that winter "officially" begins on Dec. 21 or 22, I've never been able to find anything that makes this date, which is the Northern Hemisphere's winter solstice, any kind of "official" date. Meteorologists in the USA consider the seasons to run from beginnings to ends of months. Among other things, this makes seasonal records easier to keep and averages easier to figure out. Australia's meteorologists think the same way, but with the seasons reversed. To make sure of this, I checked Australia's Commonwealth Bureau of Meteorology's Web site section on the nation's climate. Sure enough, it says: "Summer is from December to February; autumn from March to May; winter from June to August; and spring from September to November. For most of the country the hottest month is January." (Related: Australia's climate) This year (2003) the winter solstice occurs on Monday, Dec 22 at 7:04 a.m. Universal Time – the "standard" time at the longitude line that goes through Greenwich, England. (This is why it used to be called Greenwich Mean Time.) This is 2:04 a.m. Eastern Time in the USA and 11:05 p.m. Sunday, Pacific time in the USA. So, if the December solstice isn't the "official" beginning of winter in the Northern Hemisphere, what is it? It's the darkest part of the year in the Northern Hemisphere and after the solstice the days ever so slowly begin to lengthen. More precisely, the Northern Hemisphere winter solstice is the instant when the sun is directly above the Tropic of Capricorn, which is latitude 23.5 degrees south. The latitude lines runs across northern Australia, Chile, southern Brazil, and southern South Africa. At this time the sun is at its lowest point in the Northern Hemisphere's sky. You could say it's the beginning of astronomical winter. We have a lot of information about all of this on the USATODAY.com Web site. You'll find a graphic and links to this information by going to Earth's tilt creates seasons. Meteorological winter is different, as the National Oceanic and Atmospheric Administraion noted in a Dec. 22, 2003 press release: "What many people don't know is that there is another kind of winter called meteorological winter" said Steve Kuhl, warning coordination meteorologist with the NOAA National Weather Service in Washington, D.C. For weather watchers, meteorological winter is the three month period of December, January, and February. In northern locations, meteorological winter begains long before the winter solstice, the NOAA press release says. While the meteorological seasons noted above agree pretty well with the kind of weather people in most middle latitude places experience, there are other ways to look at the seasons. For example, the Commonwealth Bureau of Meteorology's Web site has a section on Indigenous Weather Knowledge. If you go to this page, you'll see four red dots on a map of Australia. Clicking on these dots takes you to information about the seasons of four different groups in north-central Australia. Two of them have five seasons, one only three, and the fourth has six seasons. These peoples live in Australia's tropics — north of the Tropic of Capricorn — which means temperatures stay pretty much the same all year, but the amount of clouds and rain change. Keith Heidorn, who runs The Weather Doctor Web site has another way to look at the middle latitude seasons: The solar seasons. By this system, he notes, "The quarter of the year having the most potential solar energy and longest days is Solar Summer; and the quarter having the least potential solar energy and shortest days (is) Solar Winter." Spring and fall, of course, are the seasons in between winter and summer. These seasons begin on the "cross quarter days," which are (roughly) half way between the solstices and equinoxes. In the western world, cross quarter days — or days close to them — are traditional holidays. Probably the best known of these in the USA is Groundhog Day. May day is another. (Related Weather Doctor columns: Celebrating Ground Hog Day and Celebrating May Day) All in all, the weather in most places is too disorderly to be confined to rigid "seasons." Naming seasons and selecting beginning and ending dates are one of the ways we humans try to bring a little order to the disorderly atmosphere. We shouldn't be surprised when nature doesn't always go along. When a foot of snow falls on the Northeast on Dec. 15, nothing is wrong with the weather — nature is just reminding us who's boss. |
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