3. FACTORS THAT INFLUENCE CLIMATE 1. ATMOSPHERIC PRESSURE: -
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Is the weight of air on the Earth’s surface We can measure it with a barometer It express in millibars (mb) The average atmospheric pressure at sea level is 1,013 mb. We can show it on a map, using isobars ISOBARS: lines that connet places with the same atmospgeric pressure. We can distinguish: 1. High pressure areas = anticyclones (H) 2. Low pressure areas= depressions (L) Pressure varies according to: 1. Temperature: hot air weights less than cold air. 2. Altiude: there is less pressure at high altitud
3. FACTORS THAT INFLUENCE CLIMATE 2. AIR MASSES -
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Air separates into air masses In each hemisphere there are air masses of : - 1. Cold polar air - 2. Hot tropical air WEATHER FRONTS: are boundaries that separate the air masses. Here, weather is unstable.
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It influences climate Near the Equator: - temperatures are higher, because sun’s rays reach the Earth in a diect angle. Near the poles: - temperatures are lower, because sun’s rays reach the Earth in a low angle. (The Earth receives less solar energy).
3. FACTORS THAT INFLUENCE CLIMATE -
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4. ALTITUDE At higher altitude, the air is hinner and loses heat. Each 1,000 metres of altitude, there is a fall of 6ยบC in temperature. In mountainous areas: - Temperatures are lower - Precipitation is bigger 5. PROXIMITY TO OCEANS Oceans and seas store more heat than the continents. As a consequence: - Temperatures are mild in coastal areas - Temperatures are more extreme inland, there is a bigger difference between maximun and minimum temperatures. Oceans and sea breezes increase the humidity of coastal areas.
3. FACTORS THAT INFLUENCE CLIMATE • WEATHER CHART/MAP : HOW TO INTERPRET IT • Weather chart : – shows the atmospheric pressure. – We use it to make the weather forecasts – Letter H= high pressure or anticyclone: – Weather is dry and stable – Letter L= Low pressure or depression: – Weather is rainy , stormy and unstable. – Isobars: lines that connect places wih the same atmospheric pressure. – Weather fronts: – Cold fronts: we use a blue line with small triangles – Warm fronts: we use a red line with small semicircles