Welcome! This page is useful to meteorologists who need help remembering units, constants, and abbreviations. Scroll down to examine or use the find function within your browser to search within the page. 

Fundamental Units

Quantity	Name of unit	Abbreviation
Length	meter	m
Mass	kilogram	kg
Time	second	s
Electrical Current	ampere	A
Temperature	kelvin	K

 

Derived Units

Quantity	Name of unit	Symbol	SI Units
Force	newton	N	kg m s-2
Pressure	pascal	Pa	N m-2 = kg m-1 s-2
Energy	joule	J	kg m2 s-2
Power	watt	W	J s-1 = kg m2 s-3
Electrical Potential Difference	volt	V	W A-1 = kg m2 s-3 A-1
Electrical Charge	coulomb	C	A s
Electrical Resistance	ohm	W	V A-1 = kg m2 s-3 A-2
Electrical Capacitance	farad	F	A s V-1 = kg-1 m-2 s4 A2
Frequency	hertz	Hz	s-1
Sound Level	decibel	dB	10 log (p1/p2)
Celsius Temperature	degree	°C	K - 273.15
Temperature Interval	degree	deg or °	either K or °C

 

Useful Unit Conversions

Quantity	English	SI
Velocity	1 mph; 1 knot	0.45 m/s; 0.514 m/s
Temperature	°F	(°F - 32)(5/9) = °C
Length	39.4 in	1 m
Pressure	1 psi	6895 Pa
Mass	1 lb	0.45 kg
Energy	1 ft lb	1.36 J
Volume	1 gal	3.8 x 10-3 m3

 

Standard Atmosphere

1 atm

1013.25 mb; 760 mmHg; 29.921 inHg; 14.7 lb in-2

 

Other Units

Quantity	Name of unit	Symbol	Fundamental Units
Volume	liter	l	10-3 m3
Pressure	millibar	mbar or mb	102 Pa

  

Decimal Multiples of Units

Multiple	Prefix	Symbol
10-1	deci	d
10-2	centi	c
10-3	milli	m
10-6	micro	m
10-9	nano	n
10-12	pico	p
10-15	femto	f
10-18	atto	a
101	deca; deka	da
102	hecto	h
103	kilo	k
106	mega	M
109	giga	G
1012	tera	T

 

Useful Physical Constants

Name of the Constant	Abbreviation	Value and Units
Universal Gas Constant	R*	8.3145 x 103 J K-1 mol-1
Boltzmann's Constant	k	1.381 x 10-23 J K-1 molecule-1
Avogadro's Number	NA	6.022 x 1023 mol-1
Stefan-Boltzmann Constant	s	5.6696 x 10-8 W m-2 K-4
Planck's Constant	h	6.6262 x 10-34 J s
Velocity of Light	c	2.998 x 108 m s-1
Permittivity of Vacuum	eo	8.85 x 10-12 C2 N-1 m-2
Average Radius of the Earth	RE	6.37 x 106 m
Mean Gravity at Earth's Surface	go , g	9.81 m s-2
Angular Velocity of Rotation of the Earth	W	7.292 x 10-5 rad s-1
Average Distance from the Center of the Sun to the Center of the Earth	d , do	1.50 x 1011 m
Solar Irradiance on a Perpendicular Plane at the mean Earth-Sun Distance	So	1.367 x 103 W m-2
Average Molecular Weight of Dry Air	Md	28.97
Gas Constant of Dry Air	Rd	287 J K-1 kg-1
Density of Dry Air at 0°C and 1000mb	rd	1.275 kg m-3
Specific Heat of Dry Air at Constant Pressure	cpd	1004 J K-1 kg-1
Specific Heat of Dry Air at Constant Volume	cvd	717 J K-1 kg-1
Thermal Conductivity of Dry Air at 0°C	k	2.40-2 J m-1 s-1 K-1
Molecular Weight of Water	Mw	18.016
Gas Constant for Water Vapor	Rv	461 J K-1 kg-1
Density of Liquid Water at 0°C	r w	1.00 x 103 kg m-3
Density of Ice at 0°	r i	0.917 x 103 kg m-3
Specific Heat of Water Vapor at Constant Pressure	cpv	1952 J K-1 kg-1
Specific Heat of Water Vapor at Constant Volume	cvv	1463 J K-1 kg-1
Specific Heat of Water Vapor at 0°C	cw	4218 J K-1 kg-1
Specific Heat of Ice at 0°C	ci	2106 J K-1 kg-1
Enthalpy (Latent Heat) of Vaporization of Water at 0°C	lv	2.50 x 106 J kg-1
Enthalpy (Latent Heat) of Vaporization of Water at 100°C	lv	2.25 x 106 J kg-1
Enthalpy (Latent Heat) of Fusion of Water at 0°C	lf	3.34 x 105 J kg-1
Enthalpy (Latent Heat) of Sublimation of Water at 0°C	ls	2.83 x 106 J kg-1

  

List of Other Abbreviations

An asterisk (*) denotes other abbreviations. Click on them to see other common abbreviations used.

Abbreviation(s)	Meaning
a	Radius of the Earth; Acceleration
b	Buoyancy
c	Phase Speed of a Wave
cpd	Specific Heat of Dry Air at Constant Pressure
cpv	Specific Heat of Water Vapor at Constant Pressure
cvd	Specific Heat of Dry Air at Constant Volume
cw	Specific Heat of Liquid Water
e	Internal Energy Per Unit Mass or Vapor Pressure
es	Saturation Vapor Pressure
f	Coriolis Parameter (=2W sinf)
g	Mangnitude of Gravity; Antenna Gain
g (*)	Gravity Vector
g*	Effective Gravitational Acceleration
h	Specific Enthalpy; Effective Pulse Length
i	Square Root of Negative One
i (*)	Unit Vector Along the x-axis
j (*)	Unit Vector Along the y-axis
k (*)	Unit Vector Along the z-axis
k	Zonal Wave Number
l	Mixing Length; Meridional Wave Number
m	Mass; Vertical Wave Number; Planetary Wave Number
mv	Molecular Weight of Water
n	Distance in Direction Normal to a Parcel Trajectory; Meridional Index for Equatorial Waves; Refractive Index
n (*)	Unit Vector Normal to a Surface
p	Pressure
po; ps	Standard Constant Pressure; Surface Pressure in s Coordinates
pr	Received Power
pt	Transmitted Power
q	Specific Humidity; Quasi-geostrophic Potential Vorticity; Water Vapor Mixing Ratio
qs; ws	Saturation Mixing Ratio
r	Radial Distance in Spherical Coordinates; Range to Target
r (*)	A Position Vector
s	Generalized Vertical Coordinates; Distance Along a Parcel Trajectory; Specific Entropy; Dry Static Energy
t	Time
t (*)	Unit Vector Parallel to a Parcel Trajectory
u*	Friction Velocity
u	x-component of Velocity (Eastward); Specific Internal Energy
v	y-component of Velocity (Northward); Specific Volume (may also be written as a)
w	z-component of Velocity (Upward)
w*	Vertical Motion in Log-Pressure System
x	Eastward Distance
y	Northward Distance
z	Upward Distance (Usually From Surface Of The Earth)
z*	Vertical Coordinate in Log-Pressure System
A	Area
B	Magnetic Field; Convective Available Potential Energy (CAPE)
C	Circulation
Cd	Surface Drag Coefficient
DE	Depth of Ekman Layer
Di	Drop Diameter
E	Electric Field; Evaporation Rate
F	Irradiance
F (*)	Friction
G	Universal Gravitational Constant; Zonal Force
H	Scale Height; Enthalpy
J	Heating Rate Per Unit Volume
K	Total Horizontal Wave Number; Kinetic Energy
Km	Eddy Viscosity Coefficient
L	Radiance; Angular Momentum
M	Total Mass; Mass in Convergence in Ekman Layer; Absolute Zonal Momentum; Angular Momentum
Mv	Molecular Weight of Water
N	Buoyancy Frequency; Number Density; Refractivity
P	Available Potential Energy; Precipitation Rate; Ertel Potential Vorticity
Q (*)	Q Vector
Q	Heating Rate
R	Gas Constant for Dry Air; Distance From the Axis of Rotation of the Earth to a Point on the Surface of the Earth; Diabatic Energy Generation Rate
Rmax	Maximum Unambiguous Range
R (*)	Vector in the Equatorial Plane Directed from the Axis of Rotation
R*	Universal Gas Constant
S	Entropy
So	Solar Irradiance
Sp	-T ¶ ln T / ¶ p, Stability Parameter in Pressure Coordinates
T	Absolute Temperature
U	Horizontal Velocity Scale; Internal Energy
U (*)	Three Dimensional Velocity Vector
V	Speed in Natural Coordinates; Volume
Vr	Radial Velocity
Vmax	Maximum Unambiguous Velocity
V (*)	Horizontal Velocity Vector
W	Working Rate; Vertical Motion Scale
X	Zonal Turbulent Drag Force
Z	Geopotential Height; Radar Reflectivity
a	Specific Volume (may also be written as v); Albedo
b	Scattering Coefficient; df/dy, Variation of the Coriolis Parameter with Latitude; Angular Direction of the Wind
e	Efficiency; Rate of Frictional Dissipation; Thermal Expansion Coefficient of Water; Emissivity; Ratio of Molecular Weights
g	Cp/Cv, Ratio of Specific Heats; ¶T/ ¶z, Environmental Lapse Rate
h	Vertical Component of Absolute Vorticity; Weight Function for Heating Profile
j	Latitude; Vertical Beam Width
k	Absorption Coefficient; R/Cp, Ratio of Gas Constant to Specific Heat at Constant Pressure; Rayleigh Friction Coefficient
l	Wavelength; Longitude, Positive Eastward
m	Dynamic Viscosity
n	Frequency; Angular Frequency; Kinematic Viscosity
q	Potential Temperature; Angle; Horizontal Beam Width
q'	Potential Temperature Deviation (may also be written as Q)
qe	Equivalent Potential Temperature
r	Density
s	-a ¶q/¶p, Stability Parameter In Isobaric Coordinates; -p/ps, Vertical Coordinate System in s System; Density in Isentropic Coordinates; Standard Deviation; Backscattering Cross-section; Spectrum Width; Surface Tension
sa	Absorption Cross-Section
ss	Scattering Cross-Section
t	Optical Depth; Optical Thickness; Optical Path Length; Pulse Duration
td	Diffusive Time Scale
tE	Eddy Stress
to	Surface Stress
w	Vertical Velocity (dp/dt) in Isobaric Coordinates; Angular Frequency
w (*)	Vorticity Vector
y	Horizontal Streamfunction
z	Vertical Component of Relative Vorticity
za	Vertical Component of Absolute Vorticity
C	Geopotential Tendency; Meridional Streamfunction
Ci	Ozone Mixing Ratio
G	-dT/dz, Lapse Rate of Temperature
Gd	g/Cp Dry Adiabatic Lapse Rate
Gs	Moist Adiabatic Lapse Rate
F	Geopotential
P	Exner Function
Q	Potential Temperature Deviation (may also be written as q')
W	Solid Angle; Angular Speed of Rotation of the Earth; Angular Speed of Rotation
Wrot (*)	Angular Velocity of the Earth

 

This page was created by Chris Ferry and Paul Dornsife.