Symbol
Meaning
Typical unit
Introducing
equation
T ⊥
Temperature in direction orthogonal to flow [K]
3.83
T 0
Temperature of an imaginary sub-surface
reservoir of gas molecules
[K]
3.82
T b
Brightness temperature
[K]
2.21
T i
Temperature of the ith facet on a model
nucleus
[K]
1.25
T i, T n, T e
Ion (neutral, electron) temperature
[K]
3.117, 5.38
T PERI
Time of periapsis
[s]
1.8
t R
Characteristic timescale for radiation
[s]
2.108
T S
Tensile strength
[N m
À2
]
2.36
t STP
Mean time between collisions at standard
temperature and pressure (STP)
[s]
3.29
T STP
Temperature under STP conditions
[K]
3.31
T x
Tisserand parameter with respect to planet x Unitless
1.17
u
Bulk or drift velocity of a gas or plasma in a
flow
[m s
À1 ]
3.45
u
Bulk fluid velocity vector in the conservation equations for the Boltzmann equation
[m s
À1 ]
3.95
U
Impactor velocity
[m s
À1 ]
2.128
u 1
Upstream solar wind speed
[m s
À1 ]
5.27
u sw
Flow speed of solar wind
[m s
À1 ]
4.124
u th
Fluid threshold velocity
[m s
À1 ]
2.133
ϑ
Frequency
[Hz]
V
Volume
[m
3
]
2.89
v ⊥, v k
Velocity perpendicular (parallel) to the field [m s
À1 ]
5.14
v
Mean orbital speed
[m s
À1 ]
2
v 1
Gas terminal velocity
[m s
À1 ]
3.44
v 0
Gas velocity at the surface
[m s
À1 ]
4.91
v a
Velocity of a spherical particle
[m s
À1 ]
4.89, 4.124
v col
Collision velocity
[m s
À1 ]
7.1
v ej
Velocity of ejected mass in direction normal
to the surface
[m s
À1 ]
2.35
v esc
Escape velocity
[m s
À1 ]
2.29
v g, v d
Gas (dust) velocity
[m s
À1 ]
2.98, 4.1
v gp
Velocity of the parent in the Haser model
[m s
À1 ]
3.108
v h
Heliocentric velocity
[m s
À1 ]
3.120
v H2O
Effective velocity with which water molecule leaves a particle
[m s
À1 ]
4.112
v i
Effective velocity of ejected material at the
source from the i
th facet
[m s
À1 ]
1.24
V imp
Volume of an impact crater
[m
3
]
2.97
v q
Vibrational quantum number
Unitless
3.35
(continued)
xxxii
Symbols Used
Meaning
Typical unit
Introducing
equation
T ⊥
Temperature in direction orthogonal to flow [K]
3.83
T 0
Temperature of an imaginary sub-surface
reservoir of gas molecules
[K]
3.82
T b
Brightness temperature
[K]
2.21
T i
Temperature of the ith facet on a model
nucleus
[K]
1.25
T i, T n, T e
Ion (neutral, electron) temperature
[K]
3.117, 5.38
T PERI
Time of periapsis
[s]
1.8
t R
Characteristic timescale for radiation
[s]
2.108
T S
Tensile strength
[N m
À2
]
2.36
t STP
Mean time between collisions at standard
temperature and pressure (STP)
[s]
3.29
T STP
Temperature under STP conditions
[K]
3.31
T x
Tisserand parameter with respect to planet x Unitless
1.17
u
Bulk or drift velocity of a gas or plasma in a
flow
[m s
À1 ]
3.45
u
Bulk fluid velocity vector in the conservation equations for the Boltzmann equation
[m s
À1 ]
3.95
U
Impactor velocity
[m s
À1 ]
2.128
u 1
Upstream solar wind speed
[m s
À1 ]
5.27
u sw
Flow speed of solar wind
[m s
À1 ]
4.124
u th
Fluid threshold velocity
[m s
À1 ]
2.133
ϑ
Frequency
[Hz]
V
Volume
[m
3
]
2.89
v ⊥, v k
Velocity perpendicular (parallel) to the field [m s
À1 ]
5.14
v
Mean orbital speed
[m s
À1 ]
2
v 1
Gas terminal velocity
[m s
À1 ]
3.44
v 0
Gas velocity at the surface
[m s
À1 ]
4.91
v a
Velocity of a spherical particle
[m s
À1 ]
4.89, 4.124
v col
Collision velocity
[m s
À1 ]
7.1
v ej
Velocity of ejected mass in direction normal
to the surface
[m s
À1 ]
2.35
v esc
Escape velocity
[m s
À1 ]
2.29
v g, v d
Gas (dust) velocity
[m s
À1 ]
2.98, 4.1
v gp
Velocity of the parent in the Haser model
[m s
À1 ]
3.108
v h
Heliocentric velocity
[m s
À1 ]
3.120
v H2O
Effective velocity with which water molecule leaves a particle
[m s
À1 ]
4.112
v i
Effective velocity of ejected material at the
source from the i
th facet
[m s
À1 ]
1.24
V imp
Volume of an impact crater
[m
3
]
2.97
v q
Vibrational quantum number
Unitless
3.35
(continued)
xxxii
Symbols Used