Qe: Standard symbol for radiant energy.
Qv: Standard symbol for luminous energy.
Q band: Radar bandwidth from 36-46 GHz.
Quantile: A statistic associated with a sample which indicates the
probability of selecting another sample with a value less than or equal
to the first (usually given as a percentage). A quantile-quantile (Q-Q)
plot can be generated which expresses the percentage of actual data values
less than a given value against the quantile for that value. The plot is
used to test whether the data can be regarded as samples from the assumed
probability distribution.
Quantisation: Process by which a grey value or a range of grey values
in an image is assigned a new value from a given finite set of grey values.
Quantum: Smallest (indivisible) unit or 'packet' of energy. The term
photon is often used with electromagnetic radiation.
Quick look image: Jargon term for a rough or small first image that
is often used to assess spatial coverage and cloud cover.