  The simulation of Cherenkov photon's lateral density and arrival time
distributions in Extensive Air Showers (EASs) was performed with the CORSIKA
code in the energy range: 100 GeV to 100 TeV. On the basis of this simulation
we obtained a set of approximating functions for the primary $\gamma$-ray
photons, protons and iron nuclei incident at zenith angles from 0$^\circ$ to
40$^\circ$ over different altitudes of observation. Such a parameterisation is
important for the primary particle identification, for the reconstruction of
the shower observables and hence for a more efficient disentanglement of the
$\gamma$-ray showers from the hadronic showers. From our parameterisation
analysis, we have found that even though the geometry of the lateral density
($\rho_{ch}$) and the arrival time ($t_{ch}$) distributions is different for
different primaries at a particular energy ($E$), at a particular incident
angle ($\theta$) and at a particular altitude of observation ($H$) up to a
given distance from the showe core ($R$), the distributions follow the same
mathematical functions $\rho(E,R,\theta,H) = a E^{b}\exp[-\{c R + (\theta
/d)^{2}-f H\}]$ and $t(E,R,\theta,H) = l E^{-m}\exp(n/R^{p})({\theta}^q+s)(u
{H}^2+v)$ respectively but with different values of function parameters.
