Environmental Lapse Rate

Definition

The environmental lapse rate is the rate at which the temperature of the atmosphere decreases with an increase in altitude. This concept is essential for understanding atmospheric stability, how temperature changes affect air parcels, and how different atmospheric layers interact with one another.

5 Must Know Facts For Your Next Test

1. The environmental lapse rate averages about 6.5°C per kilometer in the troposphere but can vary significantly depending on local conditions.
2. When the environmental lapse rate exceeds the dry adiabatic lapse rate, the atmosphere is considered unstable, leading to convection and potential storm development.
3. A negative environmental lapse rate indicates temperature inversion, where temperatures increase with altitude, resulting in stable atmospheric conditions.
4. The environmental lapse rate plays a crucial role in determining cloud formation, precipitation, and overall weather patterns.
5. Different layers of the atmosphere (troposphere, stratosphere, etc.) exhibit varying lapse rates that can influence air movement and weather systems.

Review Questions

• How does the environmental lapse rate influence atmospheric stability and the potential for convection?
  • The environmental lapse rate directly affects atmospheric stability by determining whether an air parcel will rise or sink. When the environmental lapse rate is greater than the dry adiabatic lapse rate, it indicates that rising air parcels will remain warmer than their surroundings, promoting convection and potentially leading to storm development. Conversely, if the lapse rate is lower, the atmosphere is stable, preventing vertical motion and inhibiting cloud formation.
• Discuss how variations in the environmental lapse rate can impact weather patterns and phenomena such as thunderstorms.
  • Variations in the environmental lapse rate can lead to different weather outcomes based on stability. A steep lapse rate suggests rapid cooling with height, which can create conditions ripe for thunderstorms as warm air rises and cools quickly. On the other hand, a shallow lapse rate might suppress vertical development, resulting in clearer skies. This variability plays a crucial role in forecasting severe weather events and understanding local climate patterns.
• Evaluate the significance of the environmental lapse rate in relation to potential temperature and adiabatic processes in the atmosphere.
  • The environmental lapse rate is significant because it influences how potential temperature is calculated and understood within adiabatic processes. By examining how an air parcel's temperature changes as it ascends or descends through different atmospheric layers with varying lapse rates, we can predict its behavior regarding stability and buoyancy. A thorough understanding of these interactions allows meteorologists to better anticipate weather changes and develop models for atmospheric dynamics.

Related terms

Dry Adiabatic Lapse Rate: The dry adiabatic lapse rate is the rate at which an unsaturated air parcel cools as it rises, typically around 9.8°C per kilometer.

Potential Temperature: Potential temperature is the temperature that an air parcel would have if it were brought adiabatically to a standard reference pressure, usually 1000 hPa.

Stability Indices: Stability indices are quantitative measures used to assess the stability or instability of the atmosphere, helping predict weather phenomena like thunderstorms and turbulence.