# What is Atmospheric Pressure? Definition, Formula, and Examples
Atmospheric pressure is a fundamental concept in physics and meteorology, describing the force exerted by the weight of air above a given point on Earth’s surface. Understanding this phenomenon is key to grasping weather patterns, aviation, and even human physiology.
## **Key Definition and Basics**
The standard atmospheric pressure definition refers to the pressure at sea level, approximately 101,325 pascals (Pa), or 1 atmosphere (atm). It decreases with altitude due to less air above.
## **Formula and Calculation**
Atmospheric pressure is calculated using the barometric formula:
**P = P₀ × e^(-Mgh/RT)**
Where P is pressure at height h, P₀ is sea-level pressure, M is molar mass of air, g is gravity, R is the gas constant, and T is temperature.
## **Real-World Examples**
– Weather Forecasting: Low pressure often indicates storms.
– Aviation: Aircraft adjust for pressure changes at different altitudes.
– Health: Changes can affect ear pressure or altitude sickness.
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### **Common Questions**
**How is atmospheric pressure measured?**
It is commonly measured using a barometer, with units like hPa, mmHg, or psi.
**Why does pressure vary with weather?**
Temperature and humidity changes alter air density, impacting pressure.
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