What causes the milky white layers found in hailstones?

The milky white layers found in hailstones are primarily caused by the rapid freezing of tiny droplets that become trapped within the layers of ice. When hailstones form in thunderstorms, they are subjected to intense updrafts that carry moisture upward into the colder regions of the atmosphere. As supercooled water droplets collide with the hailstone, they freeze almost instantly. This process traps air bubbles within the ice, which results in the characteristic cloudy or milky appearance.

The encapsulated air leads to a scattering of light, giving the layers their distinct milky color. This phenomenon highlights the dynamic nature of hailstone formation, where varying conditions lead to different visual characteristics in the final structure of the hailstone. The correct answer thus reflects the specific physical process of rapid freezing and air entrapment that creates those distinctive layers.