The document compares the environmental lapse rate and adiabatic lapse rate. The environmental lapse rate is the rate at which air temperature decreases with elevation, unaffected by water vapor saturation. The adiabatic lapse rate is the rate of temperature decrease when air is either dry or moist. It can decrease faster or slower than the environmental rate depending on stability. The major difference is the environmental lapse rate is unaffected by saturation, while the adiabatic rate takes saturation into account.

1. Environmental Lapse Rate
VS.
Adiabatic Lapse Rate

2. What is a Lapse Rate?
• A lapse rate is the rate at which
temperature of the atmosphere
decreases as the altitude increases
• The lapse rate tells us how much
the temperature is decreasing the
higher in the air we get
• The higher you are in the
atmosphere, the colder the
temperature will be
• 퐿푎푝푠푒 푅푎푡푒 = −
푑푇
푑퐴
• Equation represents the
decreasing change in temperature
over the change in altitude

3. Environmental Lapse Rate
• The rate at which air temperature decreases with elevation
• This refers to the rate of temperatures decreasing when it is not being
affected by the saturation of water vapor in the atmosphere
• However it can be affected by the stability of the air
• If the rising air parcel is colder than environment than its heavier and doesn’t
rise. Therefore it is stable
• Air is unstable when the air parcel is warmer and rises because it’s lighter
than its environment
• Environmental Lapse Rate decreases faster when air is unstable than stable
• Different from adiabatic lapse rate because adiabatic is the rate at which
temperatures decreases with altitude when the air is either moist or cold
• Measured by a balloon device called a radisonde

4. Adiabatic Lapse Rate
What is Adiabatic Lapse Rate?
• Adiabatic lapse rate is basically the
environmental lapse rate being affected
by the saturation of the atmosphere
• Air is moist when it is saturated by water
vapor and dry when there isn’t much
water vapor
• Like environmental, adiabatic can be
affected when atmosphere is stable or
not stable
Dry Adiabatic vs. Moist Adiabatic
• When the atmosphere is stable the
adiabatic rate decreases faster with
altitude than the environmental lapse
rate, but not by much
• If the adiabatic rate is dry during a
stable atmosphere than the
temperature decreases much faster
than both moist adiabatic rate and the
environmental lapse rate
• If atmosphere was unstable the dry
adiabatic would be slower than
environmental and the moist adiabatic
would be slower than both dry and
environmental

5. Recap
• Lapse Rate is the rate which temperature decreases as the altitude increases in
the air
• Environmental lapse rate is the rate which temperatures decreases when the rate
is not affected by the saturation of the air
• Environmental lapse rate decreases faster when the atmosphere is unstable
rather than stable
• Adiabatic lapse rate is the rate of temperature decrease when air is either dry or
moist
• Could decrease either faster or slower than the environmental rate based on if the
air is stable or not
• Major difference between the two is, Environmental lapse rate is the rate when air
saturation is put into account and adiabatic is the lapse rate affected by saturation
of the atmosphere

6. Thank You For Watching
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