Earth Science - Other

What causes Winter to Occur

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"What causes Winter to Occur"
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Some people like the variety of seasonal changes . Others would rather have warm temperatures all year around. Unfortunately, for the latter group, there are only a limited number of places on Earth where this is possible. Most locations on this planet will experience different seasons. In some locations, such as the upper midwest region of North America, the different seasons can bring forth quite extreme variations in air temperature, depending on what time of year it is. For example, a place like Wisconsin can be as cold as 40 degrees below zero Fahrenheit in January or as hot as 105 above zero in July or August.

What causes seasonal changes in the first place?

The answer lies in the tilt of the Earth's axis. The North and South poles represent the top and bottom of this almost-spherical or ball-shaped planet. However, they are tilted about 22.5 degrees off from a perfect vertical position. The Earth thus acts sort of like a gigantic top that spins with a slight tilt. As the planet makes one spin every 24 hours, it is also making its way around the sun throughout the course of a year.

Now here is where things become interesting. If the Earth's axis had no tilt, this would result in the North and South poles being perfectly straight up and down from each other. If this were the case, then there would be no seasonal changes in any particular region of the planet's surface. Thus, using a place like Wisconsin as in the example above, the temperatures would hover at around 45 degrees Fahrenheit all year around as opposed to being much colder in the winter and much warmer in the summer.

Since this isn't the case, different seasons exist. That 22.5 degree tilt of the Earth's axis affects the amount of sunlight different portions of the earth receive. Earth is divided horizontally by the equator, which is also the warmest part of the planet. It is also divided vertically by hemispheres. Anything north of the equator is said to be in the northern hemisphere while anything south is conversely part of the southern hemisphere. There are two times of year when the earth reaches its maximum amount of tilt. The planet gets tilted a bit more during these times for the following reasons: Earth's orbit around the sun isn't perfectly circular, but elliptical. Because of this, Earth is tilted a bit more due to the gravitational pull of the sun at these times, which are known as solstices.

In the northern hemisphere, the summer solstice occurs at or around June 21 and the winter solstice arrives at or around December 21. However, in the southern hemisphere, the exact opposite occurs. The summer solstice is in December while the winter solstice is in June!

Thus, winter occurs when either hemisphere receives the least amount of sunlight. The northern hemisphere in particular experiences cold air masses during the winter months as a result of less intense sunlight. The southern hemisphere does not experience the brutally cold winters of the northern hemisphere because there is much more ocean water south of the equator. Even when ocean water is cooled in the winter, the upper layers continuously recirculate warm surface water.

As hinted at above, some people (including the author to this article) dread the onset of winter and despise the cold weather and snow that accompanies this season in northern regions. Winter occurs everywhere on Earth, but for such individuals, it is far more agreeable in latitudes roughly in the middle of the planet that enjoy tropical climates. As such, the "snowbirds" who flock to these regions year after year will be joined by one more person the split second that becomes viable.

More about this author: Patrick Sills

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