Pressure The Result of Molecular Collisions

Air can hold up a jumbo jet or knock down a building. How As we just discussed, air contains gaseous atoms and molecules in constant motion. The particles collide with each other and with the surfaces around them. Each collision exerts only a small force, but when the forces of the many particles are summed, they quickly add up. The result of the constant collisions between the atoms or molecules in a gas and the surfaces around them is pressure. Because of pressure, we can drink from straws, inflate basketballs, and breathe. Variation in pressure in Earth s atmosphere creates wind, and changes in pressure help us to predict weather. Pressure is aU around us and inside of us. The pressure that a gas sample exerts is the force that results from the collisions of gas particles divided by the area of the surface with which they collide  

The map shows a typhoon off the northeast coast of Japan. The isobars, or lines of constant pressure, are labeled in hectopascals (100 Pa). 

Density A low density of gas particles results in low pressure. A high density of gas particles results in high pressure. 

The discomfort you may feel in your ears upon ascending a mountain is caused by a pressure imbalance between the cavities in your ears and the outside air. 

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