Atmospheric Pressure

• Reason for aircraft pressurisation

  If the air pressure is too low, humans cannot take in oxygen quickly enough to meet their bodies’ needs
• Reasons why atmospheric pressure decreases the higher up you go

  Less air molecules meaning less weight being exerted
• Atmospheric pressure decreases with altitude due to less air above exerting downward force on Earth's surface
• Pressure decreases the higher up you go as there are less air molecules exerting a downward force, therefore less pressure
• Atmospheric pressure refers to the weight of air pressing down on Earth's surface and can be measured using a barometer.
• Air pressure is caused by the collisions of air particles on an object