  We have computed a spherically symmetric model for the interaction of matter
ejected during the outburst of a classical nova with the stellar wind from its
optical component.This model is used to describe the intense X-ray outburst
(the peak 3-20 keV flux was ~2 Crab) of the binary system CI Camelopardalis in
1998. According to our model, the stellar wind from the optical component
heated by a strong shock wave produced when matter is ejected from the white
dwarf as the result of a thermonuclear explosion on its surface is the emission
source in the standard X-ray band. Comparison of the calculated and observed
time dependences of the mean radiation temperature and luminosity of the binary
system during its outburst has yielded very important characteristics of the
explosion.We have been able to measure the velocity of the ejected matter
immediately after the onset of the explosion for the first time: it follows
from our model that the ejected matter had a velocity of ~2700 km/s even on
0.1-0.5 day after the outburst onset and it flew with such a velocity for the
first 1-1.5 day under an external force, possibly, the radiation pressure from
the white dwarf. Subsequently, the matter probably became transparent and began
to decelerate. The time dependence of the mean radiation temperature at late
expansion phases has allowed us to estimate the mass of the ejected matter,
~10^{-7}-10^{-6} Msun. The mass loss rate in the stellar wind required to
explain the observed peak luminosity of the binary system during its outburst
has been estimated to be dM/dt ~(1-2)x10^{-6} Msun/yr.
