Why is low pressure necessary for formation of clouds in rainy season?

Answer 1

The Earth's atmosphere varies in temperature with altitude. Generally, air at ground level is warmer. As altitude increases, the air temperature falls. When the Sun is shining it warms the ground. The warm ground warms the air immediately above it. This produces a bubble of warm air that begins to rise. Warm air rises because warm air is less dense than cold air. In theory, a bubble of air at ground level will cool as it rises and expands.

When the atmosphere is at low pressure, the rising air bubble is always warmer than the surrounding air. Under conditions of low pressure, the heated air will continue to rise. As it rises it cools; but it does not cool as quickly as the surrounding air. As it is always warmer than the surrounding air, it continues rising.

Low pressure leads to unstable air conditions. When the ground is heated, the air will rise and keep rising. Eventually, the rising air will cool enough to produce condensation (cloud and rain).

When the atmosphere is at high pressure, the rising air bubble is always cooler than the surrounding air. Under conditions of high pressure, the heated air will not continue to rise. As it rises it cools; it cools more quickly than the surrounding air. Being cooler than the surrounding air, it will not rise.

High pressure leads to stable air conditions. When the ground is heated, the air will not rise. If air does not rise, rain cannot condense.

Answer 2

Consider that the pressure is low because air is converging into a center and then rising. This rising air creates a small vaccuum, lowering the pressure. And when air rises, it is forced to cool - if it cools to its dewpoint, as it nearly always does in these situations, it will condense into clouds and precipitation will soon follow.

Answer 3

Low pressure is usually associated with air rising. When air rises, it cools. If there is enough moisture in the air, some of it will condense to form clouds and potentially rain.

Answer 4

Not exactly. Rain often occurs with a low pressures system, but can occur in the absense of any larger weather system.

Answer 5

low pressure allows columns of air to rise. As the air rises, it cools and when it cools it condenses, forming clouds. If it condenses enough then you could get rain