Air pressure (or atmospheric pressure) refers to the weight of the atmosphere covering a certain area. It can also refer to the whole weight of the Earth’s atmosphere over the planet.

Basic Facts

The standard pressure at sea level is 14.696 lbs/sq2 (1.0333 kg/cm2) or 101.325 kPa (1013.25 millibar). The pressure will differ depending on the altitude and the prevailing weather condition.

But they all mean the same thing: there are several hundred pounds of pressure around every object on the planet, including people. Earth life is able to bear this weight because the pressure is just right. If the pressure is decreased or increased by too much, life will cease to exist.

Variations in Pressure

The pressure varies a bit over various points on the planet’s surface. The deviation results in varied weather patterns. For example, high pressure means fine, warm weather. Low pressure is indicative of a weather disturbance, like a storm or hurricane.

Low pressure areas can also signal the onset of a tornado. Even the pressure at sea levels change, going as low as 870 millibars. This drop can happen during strong storms.

At Mount Everest, the air pressure is the same as the average sea level pressure. Airliners travel at 16 km (10 mi) altitudes; the pressure here is a tenth of that at normal air levels.

The higher the location, the less pressure there is. This is unhealthy for people because they are deprived of oxygen. For this reason, aircraft passengers are provided artificial pressure.

If you are at 31 km (19 mi) over the surface of the Earth, the pressure is 1/100th that of the sea. At 100 km (62 mi), you are already in outer space. The pressure goes to zero.


Pressure can be used for a variety of tasks. It is used to fill up gas tanks, blowing up tires and is utilized in various appliances and industries. As stated earlier, it is an essential part of life.

Other Facts

Atmospheric pressure is comprised of colorless air. Its existence was first noticed by the physicist Evangelista Torricelli during the 1600s. He was conducting a series of experiments on vacuums. He was trying to resolve the dilemma of pump manufacturers who were trying to carry water with piston pumps higher than 30 ft in a cycle.

Torricelli filled a vacuum tube with mercury and immersed it in water. He then noticed that a force was pushing it. Torricelli discovered the force was air. This led to the invention of the barometer, which is used to determine the amount of pressure present.


The barometer is used to measure this pressure. There are many types of barometers available, and the newer models are electrical, providing very precise measurements. This is used for predicting the weather.

Since its discovery, air pressure has been used for a variety of applications, from aircraft to tires to air conditioners. Increased understanding of its properties has also made it clear how vital it is for life to thrive on this planet.