What is the environmental lapse rate and which part of the atmosphere is it relevant?

The lapse rate of nonrising air—commonly referred to as the normal, or environmental, lapse rate—is highly variable, being affected by radiation, convection, and condensation; it averages about 6.5 °C per kilometre (18.8 °F per mile) in the lower atmosphere (troposphere).

What is environmental lapse rate?

The environmental lapse rate is the rate at which temperature changes in the vertical in the troposphere, as observed by an upwards moving radiosonde. When this lapse rate is averaged out for all places and times, it is called the Standard (or Average) Lapse Rate, which is around 3.0F/1000 ft.

What causes atmospheric stability and instability?

Cause of instability Whether or not the atmosphere has stability depends partially on the moisture content. In a very dry troposphere, a temperature decrease with height less than 9.8C per kilometer ascent indicates stability, while greater changes indicate instability.

What environmental lapse rate leads to a stable atmosphere?

Note that any actual lapse rate less than 9.8 °C/1000 m in dry air results in a stable atmosphere, whereas a wet atmosphere must have an actual lapse rate of less than 3.6-5.5 °C/1000 m to be stable. Wet adiabatic lapse rates can be determined from Fig.

What is the environmental lapse rate and how is it determined quizlet?

The environmental lapse rate is the actual decrease of temperature with altitude. This is often meaured by instrumented balloon. The dry adiabatic lapse rate is the rate at which air temperature would drop with altitude due to expansion.

What is meant by atmospheric stability?

Atmospheric stability is a measure of atmospheric status which determines whether or not air will rise, sink, or be neutral. As the air parcel rises, it will expand and cool adiabatically to its dew point (i.e. the level of condensation) at which clouds are formed.

How is environmental lapse rate determined?

The environmental lapse rate is determined by the distribution of temperature in the vertical at a given time and place and should be carefully distinguished from the process lapse rate, which applies to an individual air parcel. See autoconvective lapse rate, superadiabatic lapse rate.

What is stable and unstable atmosphere?

Weather is strongly affected by how stable or unstable the atmosphere is. Stable air means that the weather is likely to be calm. Unstable air means that the weather might change quickly with very little warning. Unstable air leads to sudden thunderstorms.

What happens to the environmental lapse rate to produce absolute stability?

If the air parcel’s temperature is greater than the temperature of the surrounding air mass, the air parcel is less dense and tends to rise. When the environmental lapse rate is less than the moist adiabatic rate an air parcel cools more quickly than the surrounding air mass. This is known as absolute stability.

What is environmental lapse rate quizlet?

Why is the situation in the troposphere defined as unstable?

Air in the troposphere is considered unstable on average because the air temperature tends to decrease with height, and warm air rises.

What is the environmental lapse rate of the atmosphere?

The environmental lapse rate is a function of the adiabatic (dry air) lapse rate, moist air lapse rate, and convection processes driven by solar radiation, greenhouse effects, and other factors like volcanoes and storms.

What is the lapse rate of an altitude change?

Lapse rates are usually expressed as the amount of temperature change associated with a specified amount of altitude change, such as 9.8 K per kilometre, 0.0098 K per metre or the equivalent 5.4 °F per 1000 feet. If the atmospheric air cools with increasing altitude, the lapse rate may be expressed as a negative number.

What is the average temperature of a lapse in distance?

The average lapse rate is assumed to be 6.49 K/km (3.56 °F or 1.98 °C/1,000 ft) from sea level to 11 km (36,090 ft or 6.8 mi). From 11 km up to 20 km (65,620 ft or 12.4 mi) assume the constant temperature is −56.5 °C (−69.7 °F).

When is the atmosphere said to be absolutely stable?

The atmosphere is said to be absolutely stable if the environmental lapse rate is less than the moist adiabatic lapse rate. This means that a rising air parcel will always cool at a faster rate than the environment, even after it reaches saturation.