why do we have spring and autumn
Many people think that some parts of the year are hotter because we're nearer to the Sun, but the real reason is that
the Earth is wonky (tilted). Why do we have seasons? We have seasons because the earth is tilted (wonky) as it makes its yearly journey around the sun. The Earth's tilt The Earth's axis is tilted at an angle of 23. 5 degrees. This means that the Earth is always pointing to one side as it goes around the Sun. So, sometimes the Sun is in the direction that the Earth is pointing, but not at other times. The varying amounts of sunlight around the Earth during the year, creates the seasons. The tilt of the Earth's AXIS is the most important reason why seasons occur. We have hot summers and cold winters because of the tilt of the Earth's axis. The tilt of the Earth means the Earth will lean towards the Sun (Summer) or lean away from the Sun (Winter) 6 months later. In between these, Spring and Autumn will occur. The Earth revolves around the Sun. The North pole always points the same way as the Earth revolves around the Sun. The Earth's movement around the sun causes the seasons. The Earth takes 365. 24 days to orbit the sun. As we move around the Sun during the year, the amount of light each area of the planet receives varies in length. When the Earth's axis points towards the Sun, it is summer for that hemisphere. When the Earth's axis points away, winter can be expected. It is Summer time in countries in the Northern Hemisphere. It is Winter time in countries in the Southern Hemisphere. It is Winter time in countries in the Northern Hemisphere. It is Summer time in countries in the Southern Hemisphere. Since the tilt of the axis is 23 1/2 degrees, the north pole never points directly at the Sun. The north pole begins to move away from the Sun. The Sun rises lower in the sky so the days start getting shorter. When the Sun is at its mid-point in the sky, we reach the ' ', around 22 September.
Day and night are both 12 hours long and its the beginning of autumn. The Earth continues on its path, and our north pole starts moving towards the Sun again. The Sun moves upwards in our skies and the days continue getting longer. Again, we reach a midpoint when day and night are both 12 hours long. This is called the ' ' and happens around 21 March. Did you know? The Earth's movement around the sun causes the seasons, but it does not affect the temperatures during the seasons. Many people believe that the temperature changes because the Earth is closer to the sun in summer and farther from the sun in winter. In fact, the Earth is farthest from the sun in July and is closest to the sun at the beginning of January! The height of the sun in the sky varies with the seasons. The sun is at its heighest at 12:00pm (noon) on any gven day. In the summer the sun is higher than it is in the other three seasons. Summer Months Summer is warmer and winter is colder because of the length of our days and nights. In the summer daylight lasts longer and night time is shorter. Winter Months In winter the days are shorter and the nights longer. There is more time for the sun to warm us during long summer days. And short winter days have long, cold nights. Revolution - The Earth revolves around the Sun. Only a few parts of the world experience the classic four seasons of spring, summer, autumn and winter. Many parts of the world get only two or even one. So, what's going on? Every day, the Earth spins once on its axis. But our planet isn't perfectly upright when it spins. Thanks to a few collisions during its formation, the Earth is tilted at an angle of 23. 5 degrees. This means that as the Earth takes it annual trip around the Sun, different areas of the planet face the Sun more directly during their daylight hours at different times of the year.
The tilt also affects the daily amount of light в without it the whole planet would have 12-hour days and nights every day of the year. Australia has summer at the end of the year when the southern hemisphere is tilted towards the Sun. In summer, days are longer because more hours are spent facing the Sun. And they're hotter because we're facing the Sun more head-on в so we get hit by more rays of sunlight than if we were on an angle. The summer solstice in Australia в about December 22 в is when we have our longest day of the year. On this day the Sun is as far south in the sky as it gets в it passes directly above the Tropic of Capricorn, roughly over Rockhampton. But while we're busy planning Christmas barbecues, the northern hemisphere is tilted away from the Sun. That means there are fewer daylight hours up there and the light is spread out over a greater surface area, so it doesn't get as warm. Their shortest day в the winter solstice в happens on our longest. The tables turn six months later, when the Earth is halfway around its orbit of the Sun. The northern hemisphere's summer solstice (longest day) matches our winter solstice around June 22, when the Sun is as far north as it goes в above the Tropic of Cancer. In spring and autumn the planet isn't tilted towards or away from the Sun в it's roughly side-on. And for two days each year the Earth's tilt is exactly side-on to the Sun. The two days are called equinoxes (equal nights), and they fall in the middle of spring and autumn, usually on September 22 and March 22. On an equinox, night and day are equal length everywhere on the planet. But spring and autumn only happen in mid-latitude areas of our planet. It's a different story in the tropics and at the frozen ends of the planet. Some parts of the polar regions are so consistently cold в and the tropics so hot в they could pass for having only one season.
Even the sunniest Antarctic day is as cold as winter in most places. This is because the light reaching the bottom of the planet is at such a low angle it doesn't carry much heat. On the other hand, the tropics are consistently hot. It doesn't matter if they're tilted towards or away from the Sun, they're still closer to it than anywhere else on Earth and they get plenty of direct light and heat. But both places have two distinct seasons. In the polar regions, the main difference comes down to the amount of daylight. During 'summer', the whole area is tilted towards the Sun and flooded with sunlight. Daytime at the poles lasts for half the year. And the polar night lasts almost as long в making for one very long, dark winter. In the tropics, the difference between seasons is due to rainfall. The wet is caused by a permanent belt of storm clouds around the middle of the planet that dumps huge volumes of rain on the land or sea below. Thanks to the tilt of the planet and some super-sized sea breezes, the storm belt doesn't stay in one place. During the northern summer, the hot air over the land rises, sucking the storm belt as far north as the Tropic of Cancer, doling out monsoons wherever it goes. As the northern summer ends the storms are dragged down towards the Tropic of Capricorn, driving the southern tour of the monsoons. The belt travels across the equator twice a year, once going south and once on the way back up. If they've got the right combination of mountains, wind and sea temperature, some equatorial areas в such as Kuala Lumpur в can score two wet seasons each year. Fortunately, the Top End is far enough from the equator to just have the one wet season Thanks to Dr Blair Trevin from the Bureau of Meteorology.
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