The terms high and low pressure systems are common in weather reporting. They are sometimes confusing to tell apart. It is good to know these terms in order to clearly understand weather reports. This article explains the differences between them, and their associated weather conditions.
A high pressure system is a condition where the pressure in the atmosphere is higher than the surrounding area.
On the other hand, a low pressure system is a condition in which the pressure in the atmosphere is lower than the pressure on the surface of the earth.
|High pressure systems||Low pressure systems|
|Sinking air||Rising air|
|Air moves clockwise||Air moves anticlockwise|
|Associated with good weather such as sunny conditions||Condensation and precipitation translating to bad weather such as rainy, cloudy or snowy conditions|
The difference can be explained using the direction of movement of the air and the weather conditions associated with each.
A high pressure system works downwards and brings with it good weather, while a low pressure system works upwards and brings bad weather.
Due to the Earth’s rotation and friction on its surface, air currents are formed. When these currents move clockwise and out of the center, a space is formed at the center. The air above the center is forced to flow downward and outward to occupy this space. This is what is called a high pressure system and it is associated with favorable weather.
Conversely, a low pressure system is created when the air moves anticlockwise and towards the center. As it flows to the center, pressure accumulates, forcing air to rise. In general, rising air cools and condenses. This forms clouds that are responsible for rain.
Here is a video that can help you understand these two systems better: