Why does temperature vary around the world?
There are many reasons why the temperature varies around the world, why it is often very hot in some places but below freezing in others. The main factor in temperature is the sun, and it is because of the sun that places are not way below freezing in the first place. The sun is our main source of heat, and places that get more sun are obviously warmer than those that don’t receive as many of the sun’s rays. There are many different causes that the temperature varies around the world, and they all affect our climate in many ways.
One of the most important factors affecting temperature is latitude. Places nearer the Earth’s equator are far warmer than those near to the poles. This is due to the shape of the Earth and the way the rays of the sun hit the planet. Since the Earth is spherical, the suns rays will be far more concentrated at the equator, as the sun is always far higher in the sky, so it will concentrate its rays on a small area. And as the sun is far lower in the sky around the poles, the rays are shared over a much larger area, and the temperatures will stay down.
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Also, as you can see on the diagram, towards the poles, the sun’s rays have much further to travel through the Earth’s atmosphere before they reach the Earth than the rays at the equator. As the rays pass through the atmosphere, they lose heat in the gases, dust and cloud, so the rays are far weaker the further away from the equator they are. All this combines to make the areas near the equator warmer than those to the far north or south. This is why areas to the far north of Scotland are much colder than the south of England.
Another main factor in global temperature is the oceans and seas, and they are obviously important since they make up about 70% of the Earth. Britain’s temperatures are highly affected by the seas, as it is of course an island surrounded by water. The distance from the sea is a large factor in an area’s temperature, and it is a key reason why Britain is generally mild in winter and cool in summer. As the sea is a liquid, it is far less dense than the land, so it can be heated more. This means that the sea takes longer to warm up and longer to cool down as it retains heat better than the land.
The sea takes a long time to heat up, even while the land is warm in summer, but as the land cools rapidly in winter the sea retains its heat for much longer. This means that areas by the sea (such as Edinburgh, or many other major cities in Britain) are cool in summer as the sea warms slowly, but mild in summer. The Atlantic Ocean is very cool in summer, and this is why the east is generally warmer than the west in summer (fig. 1), but during the winter the Ocean becomes a huge reservoir of heat, and the west of Britain can often be at least a few degrees warmer than the east (fig. 2).
Another factor in temperature that is affected by the water around us is the ocean currents, which also greatly affects temperature, especially in coastal areas. These currents keep many coastal areas in Britain much warmer than they should be in winter, when many would be freezing. For example, the North Atlantic Drift Stream, which travels from Central America to Western Europe, keeps the coastal areas of the region mild in winter. But the Currents of Labrador, which drift down from the Arctic and North Canada down to South East Canada and North East USA, give this area temperatures of well below freezing in winter, despite the fact that this region and Western Europe have roughly the same altitude – if anything, Europe should be colder. Warm ocean currents tend to raise winter temperatures, while cool currents can lower summer temperatures.
Prevailing winds also affect world temperatures. The difference in temperature between the land and the sea in different seasons determines the temperature of the prevailing wind. Winds that blow over the warm seas in winter (like in Britain) or the warm land in summer (like in a Mediterranean climate) will raise temperatures while those that blow over cold land in winter or cold seas in summer lower the temperatures of the area they blow across. Since Britain’s prevailing winds are from the southwest, they are cool in summer, but mild in winter, like Britain’s general climate.
The final factor that greatly affects temperature is altitude. On Earth, temperatures decrease at about 3?F for every 1000ft of altitude, or around 0.7? for every 100m. This means that mountainous regions are often very cold, no matter the latitude they are found at. Mountain ranges are said to have mountainous climates, because the range will often have weather that is completely different from the area surrounding it. Many areas of the Scottish Highlands are over 1000m high, so they are at least 7? colder than land near the sea, no matter what the weather. There are many other examples of this around the world. The Andes Mountains stretch from Southern Chile all the way up to Colombia in South America, and the weather there is very strange. In Ecuador (named after the equator) there is always snow on the Andes, despite the fact that the equator runs right through the mountains.
The windchill factor makes mountainous areas even colder. This is because humans all lose heat in cold air, but when there is a wind blowing, we lose heat even faster. Since there is a lot of wind in these mountainous regions, there is a lot of windchill, and this also allows snow to lie for long periods of time – that’s why there is snow all year round in the Andes and in the Atlas Mountains of North Africa. Even in the Cairngorms in North Scotland, there is snow lying for over 50 days a year, and that is all due to the altitude and windchill factor.
In conclusion, there are many reasons why temperature varies around the world, and they all affect our climates in different ways. The most important factors in global temperature are the sun and the seas, and they control the heat and the winters that we get here in Britain, as well as all around the world.