Repost Of Tornado Windspeed

In theory, photogrammetry sounds rather simple. One measures the angular distance of particle movement, translates it to an actual distance (after determining the distance to the tornado) and divides it by 1/24 of a second (or whatever the film speed was). In practice, it is very complex. There are motions relative to the ground and motions relative to the center of the main funnel. The funnel itself may not be moving perpendicular to the line sight of the camera. Often it is moving towards the camera, and the highest winds (usually on the right side of the tornado) are not in view. The highest wind speeds are due to the combined effects of three motions, the forward movement of the tornado, the rotation of the tornado, and the rotation of the suction vortex. All motion is relative, and takes place in three dimensional frame. The motion picture film is only two dimensional. The wind speeds stated are not directly comparable. Some include the forward motion of the tornado, others are not.

Category:

Science & Technology

Tags:

• Photogrammetry
• Tornado
• Windspeed

[GOODY61]

This method is way too flawed to be taken seriously.

[cbehr91]

That's why it's not used much anymore. This video is from 1992.

[MonogramPictures52]

It seems like that the Parker City (farmland) Indiana had F5 Windspeeds at over 280mph

[cbehr91]

Why is that?

[cbehr91]

And Parker City and Farmland are two different towns in Indiana.

[CyrusNixes]

One more thing,

Wouldn't it be awesome if they still did this? I would pay money for someone to do photogrammetry on the Elie, Manitoba tornado, the Jarrell, TX tornado and in the Pampa, TX 'nado.

In that Significant Tornadoes update, Tom G said he did his own personal photogrammetry on the Pampa tornado and it was 300mph+.

[cbehr91]

There probably is no need to do this anymore because radar systems are so advanced that we know the wind speed of the tornadoes as they're happening. Which is probably why this was phased-out shortly after this video series was made.

[CyrusNixes]

I used to be able to recite this whole thing from memory. I would do at school - hence I had no friends.

I love how one of the tornadoes in this is so close to my house in Hawaii - and I never knew it happened until I bought the first two TVC videos when I was 8.