Atmospheric Pressure – Geography Notes PDF in English & Hindi for UPSC and Other Competitive Exams

Atmospheric Pressure: Atmospheric pressure plays a crucial role in meteorology, aviation, and the general understanding of weather and climate patterns. It influences temperature, wind, and the formation of weather systems, making it a critical factor in Earth’s atmospheric dynamics.

Atmospheric Pressure

Atmospheric pressure, also known as air pressure, is the force per unit area exerted by the weight of the Earth’s atmosphere above a specific point on the Earth’s surface. It is the result of the gravitational pull on the air molecules in the atmosphere. Here are some key points about atmospheric pressure:

  1. Units of Measurement: Atmospheric pressure is typically measured in units of pressure such as millibars (mb) or hectopascals (hPa) in the international system (SI) and inches of mercury (inHg) in the United States. The standard atmospheric pressure at sea level is approximately 1013.25 mb (or hPa) or 29.92 inHg.
  2. Variation with Altitude: Atmospheric pressure decreases with increasing altitude. This is because there is less air above as you go higher in the atmosphere. The rate at which pressure decreases with altitude is not constant and depends on factors such as temperature and humidity.
  3. Factors Affecting Pressure: Atmospheric pressure is influenced by several factors, including temperature, humidity, and the presence of weather systems (high-pressure and low-pressure systems). Warm air is associated with lower pressure, while cold air is associated with higher pressure.
  4. Measurement Instruments: Barometers are used to measure atmospheric pressure. Mercury barometers use the height of a column of mercury to indicate pressure, while aneroid barometers use a flexible metal box to detect pressure changes.
  5. Standard Pressure at Sea Level: The standard atmospheric pressure at sea level is defined as 1013.25 mb or 29.92 inHg. This standard is used as a reference for weather and aviation purposes.
  6. Effects on Weather: Changes in atmospheric pressure are closely related to weather patterns. High-pressure systems are generally associated with fair, clear weather, while low-pressure systems are associated with unsettled or stormy weather.
  7. Wind Patterns: Differences in atmospheric pressure between regions, such as between high-pressure and low-pressure systems, create pressure gradients. These pressure gradients drive the movement of air, resulting in the formation of winds.
  8. Altitude and Human Health: Lower atmospheric pressure at higher altitudes can lead to decreased oxygen levels, which can affect human health. People who are not acclimated to high altitudes may experience altitude sickness due to the reduced oxygen availability.
  9. Units Conversion: To convert between the different units of atmospheric pressure, you can use the following approximate conversions:
    • 1 mb (hPa) = 0.02953 inHg
    • 1 inHg = 33.86 mb (hPa)

Download Atmospheric Pressure Notes PDF in Hindi

Download Atmospheric Pressure Notes PDF in English

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By Team Learning Mantras