How Hail Forms Hailstorm Information

Hailstorm Information

Hail is a form of precipitation that falls in the form of ice. Hail can range in size from the size of peas to the size grapefruits – roughly 12cm in diameter. But how does hail grow to such a size?

Hailstorm information
Hailstorm information

When thunderstorms develop with solid updrafts within very unstable environments, in the right conditions hail can fall into the updraft and get dragged up several times – each time growing another layer of ice – similar in structure to onions. If the storm is particularly powerful, the updrafts are able to sustain or recycle much larger hailstones. The most powerful storms that are more likely to be able to achieve this are supercells. Supercells are storms with persistently rotating updrafts. Supercells are also storms that are long lived and virtually self sufficient in that they drive their own circulations and updraft and downdraft combinations. Their structure are also designed efficiently in that the updrafts do not compete with the downdraft. This is why they are able to sustain themselves for such a long period of time. Supercells are known to produce most of the known giant hail events. More often than not, when they hit metropolitan areas, the damage produced often runs into the tens or hundreds of millions of dollars. Recent studies have also suggested that storms that have supercell characteristics but are not supercells by pure definition can also produce giant hailstones!

Hailstone layers
Hailstone layers

Structure of a hailstone

Hailstones are very interesting to look at! When observing them, scientists can observe an onion shell layer structure of the hailstone. These layers develop because the hailstone grows as it rises and falls within the updrafts. As the hailstone moves up and down, it comes into contact with many other water droplets within the cloud and grows further and then freezes beyond the freezing layer!

 

Hailstones also form different shapes. In fact, it is often a great way to know what is happening within the storm environment. Hailstones shaped like torpedoes and also with spikes tend to be involved with turbulent activity. It is believed that melting may be involved and refreezing which explains the spikes.

giant-hailstone-shapes Hailstorm information
Hailstorm information
windscreen-punctured-by-hailstones
Hailstorm information

Hailstones particularly giant hailstones can leave severe destruction. Such hailstones can puncture the windows of cars (this one occurring during the violent hailstorm that hit Blacktown in 2007). Roof damage is also a feature as roof tiles are cracked or shattered under the impact from these hailstones.hail-damage-on-roofhailstone-on-hand

Australian Dunoon tornado revisited

A new video of the Dunoon tornado from 2007 has been gaining popularity of late. This video is a full version of tornado with most of the never seen before cuts. This tornado was a logn lived tornado by Australian standards and caused some damage to building as well as destroying a church in Dunoon. The video shows Maccadamia Nut trees being hurled around the tornado and in one case a sheet of corrugated iron is hurled into the substation to produce the famous spectacular explosion! It is however the period prior with the initial touch down and latter part of the tornado that have been added and provide a true picture of the whole event!