Weather Question: What causes differences in hail size?

Susan asked: What causes determine the size of hail in a thunderstorm?

In order to understand what causes hail size, you have to understand how hail is formed. Hail forms in thunderstorms with a strong updraft.

So what's an updraft? It's the part of a storm where air is rising.

Hail starts to form when the updraft is strong enough to carry water droplets high enough into the atmosphere that the air temperature is below freezing.

Once a hailstone starts to form, it continues growing as it collides with super-cooled water droplets that freeze on contact. The longer the hailstone stays suspended up in the top of the cloud colliding with water droplets, the larger the hail will become.

The stronger the updraft, the longer the hail stays in the cloud and the more water droplets freeze onto it. Picture it like rolling a snowball in the snow: it adds on more layers and grows and grows. Once the hail grows to a size where it's too heavy to stay up in the cloud, it will fall to the ground.