High and Low Pressure

1. By: Clay Collins, Eland Anthony, and Andrew Carney High and Low Pressure

2. What Is Air Pressure ? Air pressure is the downward pressure applied by the weight of the atmosphere.

3. High and Low Pressure • High pressure brings sunny days while low pressure brings rainy days. This happens because cold air weighs more than hot air. When you see many dark clouds that is a sign of low pressure.

4. High Pressure • The pressure is higher at the surface of the earth where air is descending slowly, too slow to feel. High air pressure is a sign of good weather. Air tends to sink near high pressure places. High pressure systems are moved by upper level winds. Also high pressure areas do not allow clouds to form.

5. Low Pressure Low pressure forms clouds, this is because the water vapor in low pressure condenses into clouds. Low pressure can also cause hurricanes. Low pressure areas exist because air is rising, leaving less pressure behind.

6. Barometer A barometer is used to measure air pressure. This instrument was invented in 1643 by the Italian scientist named Evangelista Torricelli. The mercurial barometer is a glass tube sealed at one end and filled with pure mercury. The mercury in the tube sinks a little bit, creating something that is like a vacuum. This is called the Torricellian vacuum.

7. CONCLUSION High and low pressure affects weather by causing weather to change depending on the pressure. When there's high pressure in the air, it leads to a sunny day with no clouds. When there is low pressure, then it leads to cloudy and or rainy days. The definition of air pressure is the downward pressure applied by the weight of the atmosphere.