American Meteorological Society Certification (AMS) Practice

The presence of low and high pressure systems is a defining characteristic of atmospheric circulation. This circulation is driven by uneven heating of the Earth's surface, which causes variations in air pressure. As warm air rises, it leaves behind areas of lower pressure, while cooler air descends, creating high pressure. These pressure differences drive winds and ultimately influence weather patterns.

Atmospheric circulation plays a crucial role in distributing heat and moisture around the globe, which leads to the creation of diverse weather conditions. For example, it governs the development of storm systems, precipitation patterns, and temperature variations across different regions.

Other options present different atmospheric phenomena but do not encompass the broader picture of how pressure systems interact to affect weather. For instance, thermal inversion primarily refers to a situation where warm air traps cooler air beneath it, leading to specific localized weather conditions, rather than the diverse effects associated with broader circulation patterns. Wind shear, on the other hand, describes changes in wind speed or direction with altitude, which can impact storm development but does not explain the presence of varied weather in relation to pressure systems. Stability refers to the state of the atmosphere in terms of its ability to resist vertical motion, which can influence weather but is not directly related to the existence of low and high pressure systems.