What Are the Two Big Factors That Affect Weather?

Temperature

• As with all physical systems, the earth is constantly seeking a natural balance in temperature. The tropics receive much more solar heating than the poles. This results in a temperature imbalance. It is this global temperature gradient that serves as the engine for the world's weather. Warm air is transported northward, while cold air is funneled southward. This movement creates atmospheric currents and causes air masses to interact with one another.

Air Masses

• Air masses are the vehicles on the earth's weather highways. They represent large bodies of air that have uniform properties, such as temperature and moisture content. Cold air masses form over the northern latitudes, while warm air masses form over the tropics. Dry air masses form over continental landforms, while moist air masses form over the oceans. As the currents created by temperature gradients move these different air masses over the earth's surface, they affect the types of weather encountered by people.

Weather Fronts

• Weather fronts represent the boundaries between air masses of different temperatures. Cold fronts occur when cold air masses collide with and advance into warmer air. Warm fronts occur when warm air masses collide with and advance into colder air. These boundaries represent the front lines in the planet's ongoing battle to balance temperatures. It is along these fronts that you can best see and feel the effects of temperature on the weather -- clouds, precipitation and temperature changes.

Pressure

• As with temperature, the planet is also constantly seeking a natural balance in atmospheric pressure. The earth's temperature gradient creates areas of high pressure and low pressure. This happens because warm air expands, decreasing its pressure, and cold air contracts, increasing its pressure. As a balance is sought, air always flows from areas of high pressure to areas of low pressure. This movement of air creates wind. Furthermore, the pressure differences also foster or restrict cloud development. These pressure-related factors directly impact your weather.

Pressure Systems

• High-pressure systems contain sinking, out-flowing air. This results in warm, dry air. High-pressure systems generally produce clear skies, light winds, warm temperatures and little precipitation. On the other hand, low-pressure systems contain rising, in-flowing air. This results in cloud development. Low-pressure systems generally produce cloudy skies, gusty winds, colder temperatures and moderate to heavy precipitation. Low-pressure systems are also associated with cold and warm fronts. These fronts are responsible for the majority of all weather, including the development of thunderstorms and severe weather.