Climate

• The north of Chile is extremely dry. The further south you travel in Chile, the colder and wetter it gets
• the extremely dry climate in the north of Chile is caused by a combination of three factors: a subtropical high-pressure area above the Pacific Ocean, the Humboldt Current and the Andes Mountains
• In the north of Chile, the Andes Mountains hold back moist air coming from Argentina. This air blows in from the Atlantic Ocean, meets the Andes and is forced to rise. This leads to relief rainfall on the eastern side of the Andes while Chile lies in the rain shadow: an area of low precipitation
• During an El Niño event, the warmer sea water results in more evaporation and more precipitation. The coast of Chile is battered by heavy rains, leading to flooding, ruined harvests, landslides, mudflows and other catastrophes
• El Niño’s impact is not limited to the west coast of South America, but can be felt worldwide. For example, it can trigger drought in south-east Asia and India. In the United States, El Niño leads to milder winters, fewer hurricanes and more rain along the west coast.
• What happens during an El Niño event?

  the warmer sea water results in more evaporation & more precipitation
• The Earth’s axis is tilted at an angle of 23½°.
• Because the Earth’s axis is tilted, the Sun’s rays hardly ever fall directly on the equator, but in the areas to the north and south.
• During the year, the Sun’s vertical position moves back and forth between the circles of latitude at 23½°N and 23½°S.
• The average temperature on Earth is 15C, but this canvary greatly. In the polar regions it’s cold, in the tropics it’s warm. There are five factors that greatly influence temperature. These are called temperature factors:

  Latitude: the further you are from the equator, the colder it is

  Elevation: the higher you are, the colder it is

  Distance from the sea: the further you are from the sea,the warmer it is in summer and colder in winter

  Wind and ocean currents bring in heat and cold from elsewhere

  Location of mountain ranges: sheltered by mountains ornot 
• At the equator it is warm all year round. This zone is called the tropics (or the tropical zone). As you go towards the poles – either to the north or to the south – it graduates gets colder
• Temperate means not too hot and not too cold. The part of the temperate zone that is nearest to the tropics is called the subtropics. The average temperatures in the subtropics are less hot than the tropics, but still hotter than the rest of the temperate zone.
• As you travel further towards the poles, you enter the polar regions (or polar zone)
• Precipitation caused when rising air is pushed against a mountain is called relief rainfall
• The side of a mountain that faces the wind is called the windward side. On the windward side moist air is pushed upwards, cools down and brings rain.
• The other side of the mountain is the leeward side. The leeward side is the side that’s out of the wind. The air on that side goes down and gets warmer. On that side of the mountain there is little or no precipitation. We can also say that the area behind the mountain range is in the rain shadow
• Wind is caused by differences in air pressure. The air is blown from an area with a surplus of air (high-pressure area) towards an area with a shortage of air (low-pressure area).
• Wind doesn’t blow in a straight line from a high-pressure area to a low-pressure area, but turns to the right or the left. This change in direction, or deflection, is caused by the rotation of the Earth. In the northern hemisphere the wind turns to the right, but in the southern hemisphere it turns to the left.
• The deflection that is caused by the rotation of the Earth is called theCoriolis effect
• At the equator it is always very hot so the hot air expands and rises. This creates a low: the tropical low.
• At the poles it is always very cold so the cold air contracts and sinks to earth. This creates a high: the polar high.