Atmospheric Pressure
Atmospheric pressure is the pressure exerted by the Earth's atmosphere, measured using a barometer, and its standard value is approximately 1.013 × 105 Pa.
What is Atmospheric Pressure?
The pressure exerted by the weight of the atmosphere above a given point.
Key formula / rule: Pressure exerted by a fluid column
Key points
- Define atmospheric pressure.
- Explain the factors affecting atmospheric pressure.
- Identify the instrument used to measure atmospheric pressure.
- State the standard atmospheric pressure value.
Common exam trap
Confusing atmospheric pressure with hydrostatic pressure.
Definitions
- Term
Atmospheric Pressure
- Meaning
The pressure exerted by the weight of the atmosphere above a given point.
- Term
Barometer
- Meaning
An instrument used to measure atmospheric pressure.
- Term
Pascal (Pa)
- Meaning
The SI unit of pressure, defined as one newton per square meter (N/m²).
- Term
Atmosphere (atm)
- Meaning
A unit of pressure equal to the average atmospheric pressure at sea level, approximately 101,325 Pa.
Learning objectives
Define atmospheric pressure.
Explain the factors affecting atmospheric pressure.
Identify the instrument used to measure atmospheric pressure.
State the standard atmospheric pressure value.
Relate atmospheric pressure to altitude and weather.
Formulae
- Name
Pressure exerted by a fluid column
- Note
Where P is pressure, ρ is density of the fluid, g is acceleration due to gravity, and h is the height of the fluid column. This formula is used to understand how atmospheric pressure supports a column of mercury in a barometer.
- Expression
P = ρgh
Prerequisites
Concept of Pressure (Force per unit area)
Density of fluids
Units of measurement (SI units)
Common mistakes
Confusing atmospheric pressure with hydrostatic pressure.
Assuming atmospheric pressure is constant everywhere.
Not considering the effect of altitude on pressure.
Incorrectly converting units of pressure.
Keywords
Atmospheric pressure
Barometer
Torricelli
Altitude
Pressure units
Fluid mechanics
Meteorology
Practice preview
What is the standard atmospheric pressure at sea level in Pascals?…
easy
Which instrument is commonly used to measure atmospheric pressure?…
easy
How does atmospheric pressure change with altitude?…
easy