8.8.07

Supercells & Tornadoes

The Beautiful Supercell Thundercloud
Photo Credit: Steven Maciejewski

A Tornado usually Develop from a Supercell, a type of thundercloud where it absorbs a lot of heat from the ground and condensing many many tons of gas into water and this process, releases energy. The wind and movement of the particles inside the cloud is very violent and strong.

Supercell thunderclouds usually form on evenings when it absorbs enough heat energy. These types of thunderclouds only able to be developed on a ratio of 1:1000, and every six of these clouds will form a Tornado. The U.S.A is a place where hundreds of tornadoes are being spotted every year. This is due to the 2 currents of air- a current of warm and moist air from the pacific and another is the cold and dry air from the north. These 2 currents of air will meet together on the America and it will produce a lot of thunderclouds.

Supercell Thunderclouds have a Strong and Persistent Rotating Updraft, called the Mesocyclone. The 2 currents of air, the warm and moist current which flows at a lower altitude, and the cold and dry current which flows at a higher altitude, will start spinning the inside of the supercell cloud horizontally. The heat from the land will create an updraft which will propels the spinning column of air vertically upwards. The heat of the land will also be spirally drafted upwards and the Mesocyclone has formed.

The Mesocyclone is an important part of the Supercell, as it creates a lot of destructive phenomenas, especially Tornadoes. Now let's have a journey into the supercell cloud. First, the heat from the ground rises into the cloud and being sucked up by the Mesocyclone. The water vapour and heat rises very very fast and some water form ice and drop down to the ground as hails near the centre of the Mesocyclone. Water that manage to flow upwards will become ice too, but when they falls near the ground they will melt to form Rain. Some Rain will not even touch the ground before it completely evaporated, thus forming Virga.

The Mesocyclone is slightly tilted, when the air flows up to the top it will create an Overshooting top on top of the cloud which can be seen. Some of the Air Current flows forward and it will be cooled down rapidly and drop down from the top of the thundercloud. The Cold current of air which falls from such great height is very powerful, it can hit the ground and causes damage. This is called Microburst. It's especially very dangerous to aircrafts, If an aircraft is flying forwards, firstly it will be lifted suddenly buy the reflected current of air that flows upward. After that the Aircraft will be Strike powerfully by the Strong Stream of air current, the Microburst. Due to the strong air flow, the aircraft will crash to the ground.

Below the Supercell cloud, the air around will be flowing into the Supercell, sucked in by the strong updraft of Mesocyclone. When The air is strong, the condition is right, A stream of high speed rotating and highly destructive column of air, the Vortex will tail down from the base of the cloud and Touch Down- A Tornado has formed. The strength of a tornado ranges from F0 to F5, which is the most devastating damage of a tornado. Tornado of scale F5 can spin as fast as apx. 300mph. The Fujita scale is plotted using the speed of sound at -3C, which the speed of the wind of a F5 tornado is 0.5 Mach.

Tornado causes very extreme and destructive damage to objects in it's path- Especially F5 scaled tornadoes, their damage is total. Tornadoes also Produces Infrasound, sound waves which is undetectable by the human ear. The Wider the Vortex the lower the frequency of the sound wave. The Damage of a Tornado doesn't depends on it's Size nor Shape. Only the Speed of the Wind that matters. When the Vortex is spinning at an unimaginable speed, it can root up houses and foundations, and the more dangerous phenomena- Turning tiny objects into high-speed missile projectiles. Even a tiny piece of shattered glass can kill a person or penetrate doors, under few hundred kph of speed.

Although the damage of Tornadoes are very devastating, but it only covers a small area and last for a short period of time, if compared with Hurricane. Hurricanes cover area up to few hundred miles over a few days, while tornadoes only cover a few meter to kilometres and move across a distance of few hundred meter to kilometres over a few minutes.

2 comments:

  1. could you please give my credit for my supercell photo...

    thanks steven maciejewski

    ReplyDelete
  2. Beautiful Supercell Photo.

    ReplyDelete