Symbols Used
Symbol
Meaning
Typical unit
Introducing
equation
a
Particle radius
[m]
2.133
A (J’, J 1 )
Transition probability
3.119
A, B, C, D
Fitting constants for equilibrium vapour
pressure curves
2.93, 2.94
A
Average reflectance value over a circle
around the nucleus
4.60
A 1
Fractional area of the surface at T 1
[m
2
]
2.124
A 1,2,3
Coefficients of non-gravitational forces
[AU day
À2
]
1.21
A fric
Threshold friction velocity
Unitless
2.133
Afρ
Measure of the dust production rate
[m]
4.58
a g
Surface gravitational acceleration
[m s
À2 ]
2.28
A G
A geometric factor supporting determination
of the critical period
Unitless
2.37
A H
Directional-hemispherical albedo
Unitless
2.4
a imp
Impactor radius
[m]
2.129
a m
Largest liftable dust radius
[m]
4.91
A M
Minnaert albedo
Unitless
2.76
a n
Acceleration of a neutral resonance
scattering
[m s
À2 ]
3.123
A N
Normal albedo
Unitless
2.79
a NGF
Non-gravitational acceleration of the
nucleus
[m s
À2 ]
1.26
a p
Pore radius
[m]
3.103
a s
Semi-major axis
[AU]
1
a s (θ)
Slope distribution function
[rad
À1
]
2.74
a tu
Tube radius
[m]
3.105
A V
Modified dimensionless velocity threshold
for dust motion
Unitless
2.135
(continued)
xxiii