Instruments to measure atmospheric pressure

• Fortin barometer
• Mercury barometer
• Aneroid barometer

Applications of atmospheric pressure

1. Drinking straw
   • When straw is sucked, the air velocity in straw is high
   • The air pressure in the straw is lower than atmospheric pressure
   • Air is pushed up into a straw by atmospheric pressure
2. Rubber sucker
   • When the rubber is pressed, the air is removed
   • There is low pressure inside rubber sucker (partial vacuum)
   • Atmospheric pressure is higher than pressure inside rubber
   • Rubber sucker sticks on surface
3. Siphon
   • Atmospheric pressure is higher than the pressure in the siphone
   • The atmospheric pressure acting on liquid push the liquid down to a lower container
4. Syringes
   • When the piston is pulled, the pressure in the syringe decreases
   • The pressure in the syringe is lower than atmospheric pressure
   • The atmospheric pressure at the surface force water into the syringe.
5. Vacuum cleaner
   • Vacuum fan removes air from space inside dust bag
   • The pressure in the dust bag is lower than atmospheric pressure
   • Outside air is sucked into the dust bag together with dusts