Symbol
Meaning
Typical unit
Introducing
equation
σ DR
Electron impact dissociative recombination
cross section
[m
2
]
5.38
σ en
Electron-neutral collisional cross section
[m
2
]
5.36
σ H2O
Spectral photodissociation cross section of
H 2 O
[m
2
]
5.8
σ i
Surface area of the i
th facet
[m
2
]
1.24
σ in
Ion-neutral collisional cross section
[m
2
]
3.116
σ p
Projected cross-sectional area of a spheroid [m
2
]
2.26
σ s,ph
Ionization cross section
5.5
σ T
Tidally induced stress
[N m
À2
]
2.87
σ x
Geometric cross section of the particles
[m
2
]
4.30
τ d
Dust optical depth
Unitless
4.46
τ damp
Damping timescale
[s]
2.54
τ diff
Thermal diffusive timescale
[s]
2.122
τ p
Lifetime of the parent species
[s]
3.108
τ v
Viscous stress tensor
3.61
τ ϑ
Optical depth
Unitless
3.14
φ
Rotation angle about the vector defining the
direction of the incident light
[rad]
4.19
Φ
Scattering angle weighted with the scattering function
[rad]
4.68
φ(α)
R e flected phase function
Unitless
2.1
ϕ, φ, θ
Euler angles
[rad]
2.48, 2.50,
2.51
ϕ A
Angle from the source to the interaction
point
[rad]
3.97
ϕ M
Photometric latitude
[rad]
2.77
Φ S
Single particle angular scattering function
[sr
À1
]
2.66, 4.22
ϕ th (α)
Thermal phase function
Unitless
2.18
χ
Dust to gas mass loss ratio
2.121
Ψ
Porosity
Unitless
2.115
Ψ v
Conversion of the bulk motion of the fluid
into internal energy via viscous dissipation
3.65
ω
Single-scattering albedo of the individual
particles (also that contributing to surface
scattering)
Unitless
2.65, 4.34
Ω
Collision operator
3.87
Ω d
Angular velocity of a dust particle
[rad s
À1
]
4.114
Ω f
Gyrofrequency
[Hz]
5.17
Ω N
Rotational angular velocity of the nucleus
[
day
À1
], [rad
s
À1
]
2.34, 2.105
Ω s
Solid angle (usually for radiative transfer)
[sr]
2.58
E
Specific internal energy
[J]
3.58
xxxvi
Symbols Used
Meaning
Typical unit
Introducing
equation
σ DR
Electron impact dissociative recombination
cross section
[m
2
]
5.38
σ en
Electron-neutral collisional cross section
[m
2
]
5.36
σ H2O
Spectral photodissociation cross section of
H 2 O
[m
2
]
5.8
σ i
Surface area of the i
th facet
[m
2
]
1.24
σ in
Ion-neutral collisional cross section
[m
2
]
3.116
σ p
Projected cross-sectional area of a spheroid [m
2
]
2.26
σ s,ph
Ionization cross section
5.5
σ T
Tidally induced stress
[N m
À2
]
2.87
σ x
Geometric cross section of the particles
[m
2
]
4.30
τ d
Dust optical depth
Unitless
4.46
τ damp
Damping timescale
[s]
2.54
τ diff
Thermal diffusive timescale
[s]
2.122
τ p
Lifetime of the parent species
[s]
3.108
τ v
Viscous stress tensor
3.61
τ ϑ
Optical depth
Unitless
3.14
φ
Rotation angle about the vector defining the
direction of the incident light
[rad]
4.19
Φ
Scattering angle weighted with the scattering function
[rad]
4.68
φ(α)
R e flected phase function
Unitless
2.1
ϕ, φ, θ
Euler angles
[rad]
2.48, 2.50,
2.51
ϕ A
Angle from the source to the interaction
point
[rad]
3.97
ϕ M
Photometric latitude
[rad]
2.77
Φ S
Single particle angular scattering function
[sr
À1
]
2.66, 4.22
ϕ th (α)
Thermal phase function
Unitless
2.18
χ
Dust to gas mass loss ratio
2.121
Ψ
Porosity
Unitless
2.115
Ψ v
Conversion of the bulk motion of the fluid
into internal energy via viscous dissipation
3.65
ω
Single-scattering albedo of the individual
particles (also that contributing to surface
scattering)
Unitless
2.65, 4.34
Ω
Collision operator
3.87
Ω d
Angular velocity of a dust particle
[rad s
À1
]
4.114
Ω f
Gyrofrequency
[Hz]
5.17
Ω N
Rotational angular velocity of the nucleus
[
day
À1
], [rad
s
À1
]
2.34, 2.105
Ω s
Solid angle (usually for radiative transfer)
[sr]
2.58
E
Specific internal energy
[J]
3.58
xxxvi
Symbols Used