Our concept of summer (rather than the astronomer’s definition) is built around this. Similarly, the coldest time in winter is usually a few weeks after midwinter. While the days are getting shorter, the ocean, ground and air continue to warm up. The result? The warmest time of the year for many places (but not all!) comes a few weeks after midsummer. The atmosphere, the ground, and particularly the oceans, take a long time to heat up and to cool down. However, things are somewhat more complex. In a simple universe, one would expect the longest day to be the hottest (with most time for the Sun to heat the Earth) and the shortest day to be the coldest (the most hours of darkness for things to cool down). The reason is down to how our climate behaves. In Australia, however, most people are familiar with seasons beginning on the first day of the months of March, June, September and December. Winter goes from midwinter to the spring equinox, and spring goes from the spring equinox through to midsummer. Autumn runs from that equinox to midwinter’s day. Strangely, the solstices are also known as midsummer’s day and midwinter’s day – which leads to the strange idea that winter starts at midwinter!īy this astronomical definition for the seasons, summer runs from midsummer to the autumnal equinox (when the Sun crosses the Equator). In the southern hemisphere, it is the first day of winter. To an astronomer, and to many people around the world, today marks the change of the seasons. Defining the seasons: climate or cosmology? Many websites provide this information these days - here, for example, is all that information for my home town – Toowoomba, in southeast Queensland. It’s easy to find out when the Sun will rise and set at your location. That will bring with it the longest day for those in the southern hemisphere, and the shortest for those in the north. In six months’ time, on December 22 this year, we will have the other solstice – marking the point at which the Sun is at its most southerly point in the sky. Why the sunrise is still later after the winter solstice shortest day This also means the shortest period of daylight of the calendar year.įor the northern hemisphere, the situation is reversed – the summer solstice places the noonday Sun high in the sky, with the longest period of daylight of the year. When the Sun is farthest north in the sky, it will appear lowest in the sky at noon from locations in the southern hemisphere. A map of the entire night sky, like a map of the Earth, showing (in red) the path followed by the Sun through the course of the year - a path known as the ‘ecliptic’.
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