  Using hydrodynamic simulations, we study the mass loss due to
supernova-driven outflows from Milky Way type disk galaxies, paying particular
attention to the effect of the extended hot halo gas. We find that the total
mass loss at inner radii scales roughly linearly with total mass of stars
formed, and that the mass loading factor at the virial radius can be several
times its value at inner radii because of the swept up hot halo gas. The
temperature distribution of the outflowing material in the inner region ($\sim
$10 kpc) is bimodal in nature, peaking at $10^5$ K and $10^{6.5}$ K,
responsible for optical and X-ray emission, respectively. The contribution of
cold/warm gas with temperature $\le 10^{5.5}$ K to the outflow rate within 10
kpc is $\approx 0.3\hbox{--}0.5$. The warm mass loading factor, $\eta_{3e5}$
($T\le 3 \times 10^5$ K) is related to the mass loading factor at the virial
radius ($\eta_{v}$) as $\eta_{v} \approx 25\, \eta_{3e5}\,
\left(\mbox{SFR}/{\rm M}_\odot{\rm yr}^{-1} \right)^{-0.15}$ for a baryon
fraction of 0.1 and a starburst period of 50 Myr. We also discuss the effect of
multiple bursts that are separated by both short and long periods. The outflow
speed at the virial radius is close to the sound speed in the hot halo,
$\lesssim 200$ km s$^{-1}$. We identify two `sequences' of outflowing cold gas
at small scales: a fast ($\approx 500$ km~s$^{-1}$) sequence, driven by the
unshocked free-wind; and a slow sequence ($\approx \pm 100$ km s$^{-1}$) at the
conical interface of the superwind and the hot halo.
