Storm distance and perspective

[Mike Hollingshead]

I saw something on Tony L's vid the other day during the May 12 Attica tor close encounter that reminded me of a topic I wanted to start. That is distance perspective on video and in person. It really can be a hard thing to judge from either in person or on video, mainly on video. When one watches a video and the segment is zoomed all the way out they must remember then that the view they are seeing is making the stuff look further away then it really was.

What I noticed on his close encounter was very similar to what I noticed in person May 16 this year when the tornado first developed and it was due west of me. It seemed really damn close and perhaps it was quite close(less then 1/4 mile) but it didn't take much driving north before the perspective rapidly changed and it didn't look that close to this n-s highway now looking back sw at it(not comparing distance from it now, but looking at the distance it is west of the road from the new spot). It was very similar to what I saw on Tony's as he was racing it south and he got next to it. It looked extremely close. Then just a few moments later as he gets further south(I presume south) it was like I was watching my segment again and it seemed to be much further west of the road then I was thinking when he was next to it. I realize at first we were both much closer to the tor, but it is just amazing to me when one moves perpendicular to it for a short bit and look back at it it seems much further west of the location you were previously in. Maybe because when you are just that little bit further from it the video wide angle exponetially exagerates the apparent distance. I bet that is it. Any thoughts or things you've noticed?

 

[Shane Adams]

My May 3, 1999 Minco, OK tornado segment is a lot like the one you describe here, except the tornado was approaching from the SW moving NE/NNE as we were driving west. As we stopped and did a uie to turn and drive back east out of the path, the tornado was so close that I could only see debris/condensation mist/filament looking stuff.....basically it was too close to really "see" at the base. But once we turned back around and started driving east, the tornado stayed south of the road for about the amount of time it took us to drive a half mile at only 40mph or so. I think in my case the tornado was fairly close, maybe not as close as it looked from directly in the path, but it also appeared to change direction of movement from NNe to ENE for a period of time as we drove east (out ahead of it).

Originally I estimated its distance from us at its closest to around 1/4 mile; however after countless views of the video, I'm more apt to believe it to be around a 1/2 mile away. Still close enough, but an interesting topic and an observation that's valid to the original point.

 

[Glenn Rivers]

I have noticed on many chaser videos that the chaser often thinks the tornado is closer than it realy is. Forgive me, I don't know who took the video that I am going to refer to, but the soundbite "Levern is going to get nailed" will clue you into the video I am talking about. At one point the chaser thinks that the tor is only 1/4 mile ahead, but it looked a lot further away to me. It took the chaser something like several minutes to get to the damage path driving at a good clip, something that should have been acomplished in 30 seconds if the thing was only 1/4 of a mile away.

The tor kicked up a very wide dust collar that must have been at least 1/2 a mile wide or more, yet the dust collar never took up the entire view finder. I don't think that it would be geometricaly possible to keep the whole tornado and its dust collar in the view finder if it had really been only 1/4 mile away. What do the rest of you think?

 

[Shane Adams]

You're talking about the video of the May 15, 1991 Laverne, OK tornado, in particular the one shot by an OKC news crew. I agree, this video's narrator was waaay off in guesstimating the distance they were from that tornado. IMO it was a combination of excitement (natural) and trying to sensationalize or sell the moment (programmed).

 

[fplowman]

Depth perception can be difficult.. I was out and about one evening.. and saw a supercell forming to the east.. i started to drive towards it had a camera.. it had lots of lightning as dusk fell. It was late and because it was getting dark I stopped after about 20 or 30 miles and decided not to chase it. I filmed the lightning and storm footage over what was Paola Ks.

I must say my head was in my ass and wasnt even watching forecasts etc. for the day.. Totally un prepared.. no NWS radio or anything..

When i got home and looked at radar it was over Joplin 120 miles away I would guess.. I was like wow..

Ok so another subject similiar.. May 29th Jamestown Wedge.. I have it on Film.. we thought it was maybe 1/2 mile wide.. i was looking at light poles and land sections way out in the distance counting the poles and using the section as a reference or trying in the excitement to get an idea in my mind how big that sucker was..

Everyone else came back with mile wide wedge.. lol

I call it 3/4's of a mile and split the difference.. It was a big SOB though And Ill never forget it.. My largest one yet.. i am still in Awe..

 

[Scott Currens]

cloud-base

In my experience, chasers (including myself) almost always think they are closer to a tornado than they really are. In an attempt to improve my estimation of distance in the near tornado environment, I often go back to filming locations and measure the distance to the damage track.

What I have found is that on high-based storms such as June 12th Mulvane, KS I am likely to greatly underestimate the distance I am from the tornado. Conversely on low cloud-base situations I am more likely to accurately estimate distance, or in the case of the May 12th Harper F4 overestimate the distance.

Does this apply to other chasers? I don’t know, but it is food for thought.

Make a list of the times you thought a tornado was (closer to)/(further away) than it really was. Is there any relationship to how high the cloud bases are?

 

[fplowman]

again i find dead reckoning to work best.. sections and electric poles

 

[Glen Romine]

I think it also 'helps' to have some targets on the horizon to help with estimating distance. I've had occasions where I thought I was getting closer, only to crest the next hill and find it still a good distance away. With nothing but grass/crops, you don't really have much of a reference. Give me a recognizable landmark and I can probably better estimate the distance. If you are lucky enough for the tornado to cross a road with power poles, agree you can count the poles for a better estimate if you are within 1/2 mile or so, and the point about cloud base height I think is excellent - certainly the perspective is illusionary without taking this into account. I would think the occasion of underestimating distance is a rare one. I can think of many video segments where the videographer exclaims they are looking at a very wide tornado from relatively close distance - and apparently didn't pay much attention during high school trigonometry. Quick check - if you are looking at a mile wide tornado, and you are one mile from it, what is your field of view of the tornado? What percentage of your view out the windshield would this occupy? Better be wider than the rear view mirror

Glen

 

[Mike Hollingshead]

I agree with the size of the tornado estimation usually being way off. I think it's worse then distance judging(for people). I wish I knew just how far west of the road the May 16 tor was as that would help me in the future on distance judging. I watched the video again last night and realized even after I moved north and I look back and try and judge it that it wasn't very far west of the highway. It just wasn't a real large tornado so that probably helps it seem further away when looking back at it after moving. I try and picture city blocks(or an avg one) in the gap and between 2-4 seems about right. It also helps to try and picture a track from high school, where 4 laps are equal to 1 mile or one lap a 1/4, or basically one length to 1/8 a mile. So if the tornado is 1/8 a mile away it is really damn close. It is much easier to guess the distance as it is happening then it is later on video as video more often then not makes things look further away, unless one is obviously zoomed in.

 

[Jason_Politte]

Re: cloud-base

What I have found is that on high-based storms such as June 12th Mulvane, KS I am likely to greatly underestimate the distance I am from the tornado. Conversely on low cloud-base situations I am more likely to accurately estimate distance, or in the case of the May 12th Harper F4 overestimate the distance.

I'll second the Mulvane observation. I didn't realize how close we actually were to the tornado when it was crossing the road until the debris swirl became visible.

You hit the nail on the head, Scott. Because tornadoes take on many different forms of all shapes and sizes, it's extremely difficult to judge just how far away one is without being able to use something nearby or on the horizon for perspective, and even then it's far from being easy. I've found though that being able to actually see the ground contact point helps immensely in judging distance.

Jason