Thunderstorm Hazards > Tornadoes
Learning Goal 4g. Identify thunderstorm hazards to flight &
how to avoid them. Tornadoes.
Tornadoes are violently rotating columns of air between thunderstorm (cumulonimbus) clouds and the ground. Sometimes the tornado is invisible. More often, either cloud droplets (condensation funnel cloud), dirt and debris stirred up from the ground (debris cloud), or both, make the tornado funnel visible.
The strongest, most violent tornadoes come from the strongest thunderstorms called supercell thunderstorms. Tornadoes have a wide variety of shapes, as shown in the following diagram:
Pilots should NEVER
be in or near a tornadic thunderstorm, because tornado winds can rip
the wings off the aircraft and cause it to crash, and the debris (small
rocks, broken pieces of buildings, etc.) moving at high speed are like
bullets shooting at the aircraft.
Sadly, this video shows what happens when a news helicoptor gets too close to a tornado. https://www.youtube.com/watch?v=tlN5FMOm23M
The table below shows ranges of rotational speeds for tornadoes, and the corresponding Enhanced Fujita (EF) tornado damage intensity scale:
The problem is that it is difficult to forecast in advance which supercell thunderstorms will have tornadoes. So pilots should always stay out of supercell thunderstorms. Even without tornadoes, these storms have violent winds and hail that could cause an aircraft to crash. In North America, pilots must remain 20 nautical miles or more from all severe thunderstorms.
That said, tornadoes are fun to chase by car on the ground if you take appropriate safety procautions. A wonderful video about the difficulties of storm chasing: https://www.youtube.com/watch?v=VsxFw1Ulp2A.
| Aside: When I was a young pilot, I brought along some friends and took off in a rented airplane immediatly AFTER a line of thunderstorms had passed (i.e. the thunderstorms were moving away). We were chasing after the thunderstorms, looking for tornado damage on the ground. We didn't see much tornado damage. But we did end up with a very messy aircraft as my passengers were using their barf bags — the air is still very gusty and turbulent behind the thunderstorm line. Cleaning vomit out of an aircraft was not much fun, so I never chased tornadic thunderstorms again by aircraft. |
Key words: condensation funnel, cumulonimbus, debris cloud, Enhanced Fujita (EF) scale, funnel cloud, supercell thunderstorm, tornado, tornado funnel
Image credits. All figures by Roland Stull, except photo A tornado approaching Elie, Manitoba © User:Justin1569 / Wikimedia Commons / CC BY-SA 3.0.