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LapseRate

Lapserate, typically written as lapse rate, is a term used in atmospheric science to describe how a physical quantity changes with height in the vertical direction. The most common focus is on temperature, but lapse rate can also apply to other variables such as humidity or pressure. It is defined as the vertical gradient dX/dz, where z denotes altitude.

In meteorology, the environmental lapse rate (ELR) refers to the actual rate at which air temperature decreases

Two idealized lapse rates often discussed alongside the ELR are the dry adiabatic lapse rate (DALR) and

The sign convention commonly used is that temperature tends to decrease with height, so lapse rates have

with
height
at
a
given
time
and
place.
In
the
lower
atmosphere,
the
ELR
is
typically
about
6.5
degrees
Celsius
per
kilometer
(6.5
K/km),
but
it
can
vary
with
weather,
latitude,
season,
and
terrain.
The
ELR
is
a
key
parameter
in
assessing
atmospheric
stability
and
the
potential
for
convection.
the
saturated
adiabatic
lapse
rate
(SALR).
The
DALR
is
about
9.8
C/km
and
describes
the
temperature
change
of
a
rising,
unsaturated
air
parcel
as
it
expands
and
cools
adiabatically.
The
SALR,
which
applies
when
the
parcel
is
saturated
and
condensation
occurs,
is
lower
and
range
typically
from
about
4
to
7
C/km,
depending
on
temperature
and
moisture.
positive
magnitudes
but
negative
dT/dz.
Lapse
rates
are
central
to
stability
analyses,
influencing
cloud
formation,
weather
development,
and
aircraft
flight
conditions.