Atmospheric pressure winds and rainfall are the significant variables that are responsible for changing the weather of any place. These two are interconnected as pressure winds on condensation forms clouds that eventually cause precipitation (rainfall). The winds are the horizontal motion of air that travels from high pressure towards lower pressure. These winds are also responsible for causing storms.
Rainfall can be described as the quantity of water falling to the ground in a given period at a given place. These water droplets descend from the cloud to the earth’s surface. As we know, water droplets condense to form clouds and on becoming quite heavy, these droplets fall in the form of rain.
Pressure of Winds
The pressure of winds varies depending upon the area concerning the time under observation. The unequal distribution of sun warmth is the reason for it. The warmer regions have lower pressure winds than the colder regions.
- Low-Pressure System: A low-pressure system in geography indicates an area with lower pressure concerning its surrounding areas. As already mentioned, winds tend to flow from higher pressure areas to lower pressure areas. Therefore, the air will rise in this system and the water vapour condenses. These clouds may cause rainfall after getting suitable conditions. The pressure winds of the low-pressure system spin anticlockwise to the North of the Equator due to the Coriolis Effect i.e. due to the Earth’s rotation. On the other hand, these winds flow clockwise towards the South, this flow is called the cyclonic flow of winds.
- High-Pressure System: A high-pressure system in geography indicates an area with higher pressure concerning its surrounding areas. Therefore, the winds blow away from these areas. To cover up the space, the air from other higher regions blows towards it. If compared to low-pressure systems, the winds of the high-pressure system flow in opposite direction. The winds spin clockwise in the North whereas anticlockwise in the South of the equator. This type of flow is the anticyclonic flow.
Factors affecting Flow of Pressure Winds
Several factors affect the airflow of winds. These are as follows:
- Pressure Gradient Force: Pressure gradient force is the change of pressure concerning distance. The wind direction is always towards the change of pressure. These are perpendicular towards the isobars.
- Frictional Force: The earth’s surface is not regular causing hurdles in the flow of wind in the form of friction. The frictional force changes the angle and speed of flow of winds over the isobars. Sometimes, it can also change the direction of the wind. The oceans have smooth surfaces with lesser friction than the uneven land surfaces with greater friction. Therefore, the winds blew at a higher speed over the oceans than the uneven surfaces.
- Coriolis Force: As a result of Earth’s rotation, the winds deflect from their original path, known as the Coriolis effect. The Coriolis effect can only change the direction of the wind without changing its speed and is only present in moving air. The air deflects towards the right in Northern Hemisphere whereas it deflects towards the left in Southern Hemisphere. This force increases with an increase in velocity, latitude, and air mass.
Rainfall
Rainfall is the measurement or amount of waterfall (precipitation) from clouds at a given time of a particular area under concern. The rainfall is unevenly distributed all over the globe. Some parts get flooded due to rainfall whereas some remain drought.
Factors affecting Rainfall
Several factors affect the rainfall such as air pressure, temperature, density etc. These factors are as follows:
- Latitude
- Amount of solar energy received
- Ocean Currents
- The distribution of air pressure systems and global winds
- Existence of a mountain barrier.
- Nearness to large bodies of water
Types of Rainfall
There are three basic types of rainfall. These are as follows:
- Relief Rainfall: When the air blows over the sea and is then forced over an area of high land, relief rainfall occurs. The air blown gets cooled causing precipitation.
- Frontal Rainfall: When hot air blows towards the cold air, the moisture present in the warm air condenses. And on cooling, it causes frontal rainfall.
- Convectional Rainfall: The hot air of tropical regions rises in convectional currents and condenses forming clouds. These clouds on cooling cause convectional rainfall.
Conclusion
Atmospheric pressure winds and rainfall are the significant variables that are responsible for changing the weather of any place. These two are interconnected as pressure winds on condensation forms clouds that eventually cause precipitation (rainfall). The pressure of winds varies depending upon the area concerning the time under observation. The unequal distribution of sun warmth is the reason for it. The warmer regions have lower pressure winds than the colder regions. A low-pressure system in geography indicates an area with lower pressure with respect to its surrounding areas. A high-pressure system in geography indicates an area with higher pressure with respect to its surrounding areas. Several factors affect the rainfall such as air pressure, temperature, density etc. There are three basic types of rainfall.
