How does autumn occur

Ben Davis February 10, How does autumn and spring occur? What are the 7 seasons? What is the first full day of spring? Why is March 21 the first day of spring? Again, we reach a midpoint when day and night are both 12 hours long. This is called the ' vernal or spring equinox ' and happens around 21 March. 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! During the summer, the sun's rays hit the Earth at a steep angle because the sun is higher in the sky. The light does not spread out very much, thus increasing the amount of energy hitting any given spot.

The long daylight hours during the summer months allow the Earth plenty of time to reach warm temperatures. This is why the days are hotter in the summer months.

Because the sun is higher in the sky our shadows are shorter than they are in the the other three seasons. During the winter, the sun's rays hit the Earth at a shallow angle because the sun is lower in the sky. These rays are more spread out, which minimizes the amount of energy that hits any given spot.

The long nights and short days prevent the Earth from warming up. This is why we have cold winters. 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 — without it the whole planet would have 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 — so we get hit by more rays of sunlight than if we were on an angle.

The summer solstice in Australia — about December 22 — 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 — 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 — the winter solstice — 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 — above the Tropic of Cancer.

In spring and autumn the planet isn't tilted towards or away from the Sun — it's roughly side-on. And for two days each year the Earth's tilt is exactly side-on to the Sun.

The word autumn entered English from the French automne and didn't become common usage until the 18th century. Autumn begins There are two different dates when autumn could be said to begin. Trees prepare for winter One of the most stunning signs of autumn is the turning of the leaves. The chemistry of colour Chlorophyll is the chemical which makes tree leaves green and as it declines other chemicals become more prominent in the leaves.

People born in Autumn live longer A study in the Journal of Aging Research found that babies born during the autumn months are more likely to live to than those born during the rest of the year. The days get shorter The word equinox comes from the Latin equi meaning equal and nox meaning night accounting for the equinox marking the time when day and night are of equal length. A date for your diary - 24 September Generally speaking, the autumn equinox always falls on either 22 or 23 September, but not quite always.

Persephone's return In Greek mythology, autumn began when Persephone was abducted by Hades to be the Queen of the Underworld.