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What Happens When Unstable Air Is Forced?

Forecasters strive to predict future weather patterns based on atmospheric data and observation. The atmosphere may appear empty, with just air and clouds floating overhead. However, air can possess stable and unstable properties, contributing to extreme weather, such as thunderstorms. Air is constantly rising and falling within the atmospheric layers. At times, unstable air is forced, generating new weather effects.

Air Composition
- Air is commonly referred to as oxygen. However, the air that sustains life on the Earth is not solely oxygen. Nitrogen is a main component of air, measuring about 78.1 percent of the complete volume of air within the atmosphere. Oxygen occupies about 21 percent of the total volume. Small amounts of other gasses occupy 0.9 percent of the remaining volume. In addition, water vapor varies within the atmosphere as it interacts with the air molecules.
Forced Air Effects
- Unstable air masses can be forced upwards into the higher atmosphere layers by winds or incoming weather systems, such as high or low pressure regions. The unstable air is typically warm and humid compared to the surrounding air molecules. As a result, the forced unstable air continues to rise into the atmosphere. As it rises, the moisture within the air condenses into water vapor, creating a cloud.
After Cloud Creation
- Condensation, or converting gas molecules into liquid molecules, emits heat as the process continues generating clouds. This heat generation warms the entire air mass, enabling the air to lift higher into the atmosphere. A large volume of unstable air creating this lifting effect will eventually generate thunderstorms. The upper atmosphere retains the extra warmth from the condensation, whereas the lower atmosphere continues cooling.
Stopping the Rise
- The warm, unstable air mass continues upwards until it reaches a stable air mass. The speed that the unstable air mass accumulates as it rises can actually cause the molecules to pass a stable air region. In this case, the mass becomes neutral and slowly drifts downward. Many times, the unstable air mass must meet the tropopause layer of the atmosphere before it will sink back down. The tropopause layer is a unique atmospheric region where an increase in altitude also heightens temperature.
Contributions to Unstable Air
- The sun's movement during the day contributes to unstable air and atmosphere conditions. As the sun rises, the cool ground slowly warms. The warm ground eventually transmits heat to the air directly above it. During the course of the day, the ground and air warm to higher temperatures, generating warm air masses that begin to rise as unstable air regions.

Nature