Unlike climates that normally stays the same for much longer periods, weather changes so often each day or each hour. One day we have sunny skies, the next day we’ll have a cloudy day. Sometimes, it would be rainy one morning, and sunny and warm in the afternoon. The weather changes so often it is difficult to predict. But why and how does the weather change?
Air Mass and Pressure Areas
The weather we experience everyday will depend largely on the air mass over the area and the pressure system associated with it. Air masses that come from near the poles will bring in cold air. Air masses that come from near the equator will bring in warm air.
High and low pressure systems move
The boundaries of these air masses are where the fronts are found. Low pressure areas that contribute to moving air are often found along these boundaries. Since they move, the weather of a certain area will surely change.
Changes can depend on the type of pressure. Low pressure tends to bring in cloudy conditions and precipitation. High pressure, on the other hand, tends to bring in fair weather. A high pressure from the polar regions will bring in cold air; high pressure from the tropical areas will bring in warm air. Low pressures tend to bring in cooler air, especially when a cold front moves through the area. Tropical low pressures do not have fronts. This keeps the air mild even when the weather gets unsettled.
Factors that affect weather changes
Wind Direction: The direction the air is moving from will affect the type of weather we’ll have. For example, air from the ocean will bring in more humid air. Air from the desert will bring in dry air. Air from the polar regions will bring in colder air. Just by noting the wind direction a forecaster gains an idea of what type of air mass is moving toward the forecast area.
The air flows around low pressure areas. Changes in wind direction like in a cyclone means a low pressure or a front is affecting the forecast area. A wind shifting from the south means warmer air is approaching, and a wind shifting from the north means cooler air is approaching.
When the wind changes abruptly, thunderstorm outflow has caused changes in frontal passage or wind direction. The outflow from a thunderstorm will spread most rapidly in the direction the low level winds are flowing.
Elevation: Weather will be more unsettled when air is flowing from a lower elevation towards a higher elevation. Weather tends to be more fair and calm when air is flowing from a high elevation towards a lower elevation.
Clouds: Weather tends to be cooler during the day when there are clouds that block most of the sun’s heat and UV rays. It will be warmer at night when there are clouds in the sky. The heat that has accumulated during the day can not easily dissipate at nigh because the clouds kept it inside the lower atmosphere near the ground.