Symbol

Name

(Typical) Value

Unit

a

albedo (visible)

0.306

1

A

area

m²

$\alpha$

absorption coefficient

1/m

c

volumetric density

(molecules) per m³

C

areal density

(molecules) per m²

[CO₂]

molar CO₂ fraction

350

10⁻⁶ (ppm)

$c_{\text{p}}$

specific heat (constant P)

(1.51)

kJ/kg K

$c_{\text{v}}$

specific heat (constant V)

kJ/kg K

D

downward radiation

W/m²

g

gravitational constant

9.81

m/s²

$\Gamma$

lapse rate

K/m

h

total height of atmosphere

m

k

Boltzmann constant

1.380649 × 10⁻²³

J/K

m

molecular mass (air)

4.82 × 10⁻²⁶

kg

M

atmospheric mass density

10.328

10³ kg/m²

$N_{\text{A}}$

Avogadro’s constant

6.0221476 × 10²³

1/mol

P

pressure

Pa

$P_0$

surface atmospheric pressure

1013.2

hPa

$\rho$

mass density

kg/m³

${\rho }^{\prime }$

mass density

kg/Km²

s

climate sensitivity

K per ppm

S

solar variable (W/4)

340

W/m²

$\sigma$

Stefan-Boltzmann constant

5.670374419 × 10⁻⁸

W/m² K⁴

${\sigma }_{\text{x}}$

capture cross section

m²

T

absolute temperature

K

$T_0$

surface temperature

(288)

K

$T_{\text{bb}}$

black-body temperature

254.0

K

$\tau$

optical depth

1

$\tau$

relaxation time

s

U

upward radiation

W/m²

V

volume

m³

w

radiative forcing

W/m² per ppm

W

Solar constant

1361

W/m²

z

altitude

m