Atmospheric Pressure, Essay Example

Atmospheric pressure is quite important in foretelling the weather of a particular place, but first we need to define it. Atmospheric pressure refers to the force exerted by particles of air on the underlying surface. Meteorologists usually measure the atmospheric pressure at a particular area; that is they are measuring the pressure exerted by the weight of air molecules at that particular point. Air particles are invisible but they have weight and as the weight of air increases, pressure also increases and vice versa. Atmospheric pressure is usually measured by an instrument called a barometer and that is why atmospheric pressure is sometimes referred to as barometric pressure.

When air is heated it expands and its mass reduces, implying that it becomes less dense. This creates a high pressure system, which, in real life, occurs when the air close to the earth’s surface is unevenly heated. Upon expansion, the air molecules tend to move upwards creating an empty space that needs to be occupied. This is usually due to their reduced density paving way for cooler air. The cooler air that tends to move to fill the void warms up as it sinks in. This results in a cloudless and dry weather.

On the contrary, when air over land is heated it becomes less dense, therefore it rises up. As it rises up it tends to cool. The result is condensation of the air, formation of clouds and eventually rainfall.   This is what characterizes a low pressure system. When weather forecasters predict that a low pressure system is headed your way, it implies that it will be cloudy with a high chance of rainfall.

In conclusion, atmospheric pressure is the best indicator of current and changing weather conditions if not the most important one. Weather forecasters just need to know the atmospheric pressure of a given location and the weather can be predicted. In most cases, weather forecasts are characterized by prediction of what pressure system is to be experienced at a particular area.

Works Cited

Ahrens, Donald, C. Meteorology Today: An Introduction to Weather, Climate and its Environment. 8^th Ed. Berlin: Cengage Learning, 2007. Page 236

Graham, Roger. B. & Chorley, Richard. J. Atmosphere, Weather and Climate. 8^th Ed. Berlin: Routledge, 2003 .Page 128

Thompson, Russell D. Atmospheric processes and Systems. 6^th Ed. Berlin: Routledge, 2006. Page 87