Atmospheric air pressure varies, ranging from low pressure of around 980 millibars to a high pressure of nearly 1050 millibars. Low-pressure areas are formed where two Hadley cells converge, causing air to rise. Conversely, high-pressure zones are created where the Hadley and Ferrel cells meet, leading to descending air.

High Pressure

• When air cools, it becomes denser and descends towards the ground, resulting in high pressure.
• As this cool air reaches the Earth’s surface, it warms up, causing clouds to evaporate.
• Heavy rainfall at the Equator depletes the moisture, so by the time the air reaches the subtropics, it is much drier.
• High-pressure systems are typically associated with clear skies and dry, warm weather.

Low Pressure

• Low pressure leads to the rising of warm air, which then cools and condenses to form clouds.
• Precipitation occurs as moisture falls from the atmosphere in the form of rain, sleet, snow, or hail.
• Temperature variations between day and night are minimal in low-pressure areas because cloud cover reflects solar radiation during the day and traps heat at night.