North India experienced hailstorms in January: How do they occur?

In December 2021, The Indian Meteorological Department (IMD) had predicted hailstorms in North India during the second week of January. During this period, heavy rainfall was also witnessed, and people were warned to brace for thunderstorms and sudden, intense changes in weather. The hailstorms affected regions such as Jammu and Kashmir, Ladakh, Himachal Pradesh and Uttarakhand among others. But what are hailstorms and why do they occur? Read on to learn more. 

What is hail? 
A hailstorm is a weather phenomenon in which ‘hail’ (balls of ice) fall on earth from the sky. This hail is simply a solid precipitation which is formed at high altitudes. In such regions, water droplets become extremely low in temperature and come together within a cloud to form layers of ice. Because ice is solid and heavy, the cloud is unable to hold its weight up. As a result, the hail falls to the ground. However, if the updraft of a piece of hail is stronger than gravity, it will continue to keep growing. Once it is big and heavy enough, it gets pulled down towards the surface.  

Hailstones can be extremely dangerous that can injure individuals, destroy property and damage crops. The biggest ones can be the size of an orange or grapefruit! However, a gentle fall can be fun experience. Many people like to consume hailstones, but it is advised not to do so due the levels of pollution present in the atmosphere.  

How does a hailstorm take place? 
The atmosphere needs to be under some specific conditions in order for a hailstorm to occur. They usually happen over mid-latitude continental regions. Very rarely do they occur near the poles, above the equator and over a sea or an ocean. They require the presence of a Cumulonimbus cloud which is a massive mushroom-shaped cloud usually seen during thunderstorms. It also requires powerful currents of air leaving these clouds, which are referred to as updrafts. These updrafts carry ice particles and water droplets which, in the correct atmospheric conditions, form hail. Hailstorms are classified as a mesoscale phenomenon which means that they occur in and affect only a limited area.  

What is the difference between snow and hail? 
Snow is formed when water freezes in crystal formations which leads to intricate, unique shapes. On the other hand, hail in layman’s terms, is nothing but a frozen raindrop. It is also a lot bigger in size. The former is formed when water vapour in the air cools down rapidly into solid without going through the liquid phase.