Atmospheric pressure
Introduction
Atmospheric pressure, also known as barometric pressure, is the force exerted by the weight of the atmosphere on a given surface area. It is a fundamental concept in the fields of meteorology, physics, and engineering.
Measurement and Units
Atmospheric pressure is measured using an instrument known as a barometer. The standard unit of measurement for atmospheric pressure in the International System (SI) is the pascal (Pa), named after the French physicist Blaise Pascal. One standard atmosphere (atm) is defined as 101,325 Pa.
Distribution of Atmospheric Pressure
The distribution of atmospheric pressure across the Earth's surface is not uniform. It varies with altitude, temperature, and other atmospheric conditions. The pressure decreases with increasing altitude, which is why it is harder to breathe at higher altitudes.
Factors Influencing Atmospheric Pressure
Several factors influence atmospheric pressure, including altitude, temperature, and humidity.
Altitude
The higher the altitude, the lower the atmospheric pressure. This is because the density of air decreases with height, reducing the weight of the air above and thus the pressure exerted.
Temperature
Temperature also affects atmospheric pressure. Warmer air is less dense than cooler air, so areas of warm air have lower pressure than areas of cool air. This is the principle behind the formation of weather fronts and storms.
Humidity
Humidity, or the amount of water vapor in the air, also influences atmospheric pressure. Water vapor is lighter than dry air, so humid air has a lower pressure than dry air.
Atmospheric Pressure and Weather
Atmospheric pressure plays a crucial role in weather patterns and climate. High-pressure systems are typically associated with clear, calm weather, while low-pressure systems often bring clouds and precipitation.
Health and Atmospheric Pressure
Changes in atmospheric pressure can affect human health. Some people may experience headaches, joint pain, or other symptoms when the pressure changes significantly, a phenomenon known as 'weather sensitivity'.