  Understanding the dynamics in the deposition of water droplets onto solid
surfaces is of importance from both fundamental and practical viewpoints. While
the deposition of a water droplet onto a heated surface is extensively studied,
the characteristics of depositing a droplet onto a cold surface and the
phenomena leading to such behavior remain elusive. Here we report the formation
of a triple condensate halo observed during the deposition of a water droplet
onto a cold surface, due to the interplay between droplet impact dynamics and
vapor diffusion. Two subsequent condensation stages occur during the droplet
spreading and cooling processes, engendering this unique condensate halo with
three distinctive bands. We further proposed a scaling model to interpret the
size of each band, and the model is validated by the experiments of droplets
with different impact velocity and varying substrate temperature. Our
experimental and theoretical investigation of the droplet impact dynamics and
the associated condensation unravels the mass and heat transfer among droplet,
vapor and substrate, offer a new sight for designing of heat exchange devices.
