By the meteorological calendar, the first day of winter is always 1 December ending on 28 (or 29 during a Leap Year) February. However, at the Met Office, we often use a meteorological definition of the seasons. However, the dates of the Equinox and Solstice aren't fixed due to the Earth's elliptical orbit of the Sun. Both Equinoxes and Solstices are related to the Earth's orbit around the Sun. The astronomical calendar determines the seasons due to the 23.5 degrees of tilt of the Earth's rotational axis in relation to its orbit around the Sun. This year, astronomical winter begins on 21 December 2022 and ends on 20 March 2023.įor upcoming years, the dates for astronomical winter will be: Year "Like much of the culture in some areas, knowledge was lost due to people not being able to speak language because it was forbidden," he said.The day in our calendar that marks the first day of winter usually refers to the astronomical seasons which are a result of the Earth's axis and orbit around the Sun. Tremaine Patterson, Banbai ranger at Wattle Ridge Indigenous Protected Area, near Guyra in the New England region of New South Wales, said his people had a far more fluid approach to the seasons. Indigenous seasonsĪcross the country, indigenous communities have a very different view of the seasons. So it make sense that winter centres on the coldest part of the year, plus the convenience of the season starting on the same day at the beginning of the month does make the paperwork easier.īut as with anything arbitrary and dependent on place, there are many ways to define the seasons and the tropics' wet and dry seasons are just the start. "However, it's worth noting that the coldest 90 days of the year start within a few days of June 1 almost everywhere in Australia, except in southwest WA where it's a week or two later," he said. The monthly seasons we use in Australia are skewed to be more closely aligned with our coldest three months than the astronomical seasons. Each of the seasons last three calendar months, breaking up the year into four equal parts.ĭr Trewin said why, exactly, we took on meteorological seasons when other parts of the world, like the US, had stuck with astronomical seasons was unclear. Most Australians define winter as starting on June 1 and lasting until the end of August. "Popular usage in Australia (outside the tropics) tends to follow the meteorological seasons quite strongly," Dr Trewin said. Meteorological seasons are largely defined by Gregorian calendar months. Of course, when exactly local weather conditions conspire to bring the coldest days for each location depends on more than just raw energy from the Sun. The solstice marks the middle of the time of low energy input and even then the coldest time of year is generally after the winter solstice. The same amount of energy is spread over a larger area when the hemisphere is tilted away from the Sun. "It means there is a lag associated with how long it takes us to feel on Earth the effects of this peak energy or minimum energy," Dr Moss said, which is why it makes sense not to use the solstice to mark the start of winter, or even middle of winter. The winter solstice may be the shortest day in terms of daylight and when there is least energy in the southern hemisphere, but the land, atmosphere and, especially, oceans are still cooling. It's not as intense and the heat is not as effective," Dr Moss said. "So because the energy is spread out, it also means that the Sun feels weaker. The tilt of the Earth dictates both how long the Sun is "up", as well as how much the Sun's energy spreads over the globe.Īs the southern hemisphere is tilted further from the Sun, the angle at which sunlight hits the Earth is shallower, meaning the light and energy spreads across a larger area. If the concept of opposite northern and southern hemisphere seasons is new to you, wait for your mind to be blown as snow-themed Christmas merchandise suddenly makes sense.
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