Atmospheric Lapse Rates

What does it mean?

The atmospheric lapse rate describes the reduction, or lapse of air temperature that takes place with increasing altitude. Lapse rates related to changes in altitude can also be developed for other properties of the atmosphere.
There are three types of lapse rates, Dry Adiabatic, Saturated Adiabatic and Environmental Lapse rates.

If a material changes its physical state (that is, if its pressure, volume, or temperature change) without any heat being either added to it or withdrawn from it, the change is said to be adiabatic. So, an Environmental Lapse rates refers to a change in a physical state with heat added.

What affect do Lapse rates have on the environment?

The average atmospheric lapse rate results in a temperature decrease of 3.5°F (1.94°C) per 1,000 feet (304 m) of altitude.

There are two types of lapse rates, Dry Adiabatic and Saturated Adiabatic both of which have varying temperature changes, so what are they?

Dry Adiabatic - A dry, not saturated parcel of air, has a dry adiabatic lapse rate of 1°C/100m

Saturated Adiabatic - This saturated parcel of air has a saturated adiabatic lapse rate of 0.6°C/100 m

From the atmospheric lapse rates you can tell whether the atmosphere is stable or unstable. This can be seen when the actual lapse rate is either greater or less than the dry adiabatic lapse rate. This variation from the dry adiabatic lapse rate is what determines whether the air is stable or unstable.

The vertical air temperature distribution in the atmosphere is highly variable. For dry air it ranges as follows:

1. Very stable : Temperature increases with increase in altitude. This is a "plus" temperature lapse rate, or an inversion.
2. Stable : Temperature lapse rate is less than the dry adiabatic rate, but temperature decreases with altitude increase.
3. Neutral : Temperature lapse rate is the same as the dry adiabatic rate of 5.5 degrees Fahrenheit per 1000 feet increase.
4. Unstable : Temperature lapse rate is greater than the dry adiabatic rate. It may be 6 degrees Fahrenheit or more.
5. Very unstable : Temperature lapse rate is much greater than the dry adiabatic rate, and is called super-adiabatic.

Classroom tasks:

Some tasks could include picking key words and asking for explanations. I would want students to know the main difference between lapse rates and also explain each condition for the stability of the atmosphere.

Although this isnt the best example, there could be a graph plotting exercise showing lapse rates and temperatures:

http://www.mhartman-wx.com/fcst_tools/lapse_rates.html