1. What is Atmospheric Pressure?

Atmospheric pressure is the force per unit area exerted by the weight of the atmosphere above a point. It decreases with altitude according to the barometric formula. This calculator computes pressure in pounds per square inch (psi) at a given altitude.

2. How Does the Calculator Work?

The calculator uses the barometric formula:

Where:

• \( P \) — Pressure at altitude (psi)
• \( P_0 \) — Sea level pressure (101325 Pa)
• \( M \) — Molar mass of air (0.02896 kg/mol)
• \( g \) — Gravitational acceleration (9.8 m/s²)
• \( h \) — Altitude (meters)
• \( R \) — Universal gas constant (8.314 J/(mol·K))
• \( T \) — Temperature (Kelvin)
• 6894.76 — Conversion factor from Pa to psi

Explanation: The equation models how atmospheric pressure decreases exponentially with altitude, accounting for temperature and air composition.

3. Importance of Atmospheric Pressure Calculation

Details: Accurate pressure calculation is crucial for aviation, weather forecasting, engineering design, and scientific research at different altitudes.

4. Using the Calculator

Tips: Enter sea level pressure in Pa (default is standard 101325 Pa), molar mass in kg/mol (default is dry air 0.02896 kg/mol), altitude in meters, and temperature in Kelvin. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is standard sea level pressure?
A: Standard atmospheric pressure at sea level is 101325 Pa (14.6959 psi).

Q2: How does temperature affect pressure?
A: Warmer temperatures result in slightly higher pressure at a given altitude due to air expansion.

Q3: Why use Kelvin for temperature?
A: Kelvin is an absolute temperature scale required for the gas law calculations.

Q4: How accurate is this calculation?
A: It provides a theoretical estimate. Real-world pressure varies with weather conditions and local geography.

Q5: What's the pressure at Mount Everest's summit?
A: Approximately 4.36 psi (8848m, -20°C) vs 14.7 psi at sea level.