15 replies to this topic

[Sly2001]

I may be watching totality from a shopping center or Wal-Mart parking lot. Does anyone know if lights and lamp-posts turn on during totality? If this happens, could it effect how the sharpness and detail of the corona look? Is it better to be in a non-commercial area?

Thank you!

Edited by Sly2001, 06 February 2024 - 05:59 AM.

[Cajundaddy]

I don't remember if streetlights came on in 2017 but if they did, it was not an issue for us.

Personally I prefer to observe over grass or near water in a public park with restrooms available.  Street lights *could turn on during totality but a bigger concern is heat plumes rising from a hot parking lot surface which directly affect seeing and resolution.  

[Sly2001]

What are heat plumes? I’ll be in a parking lot in the Indianapolis area. It won’t be hot on April 8. I don’t understand this issue. Please explain. Thank you!

Edited by Sly2001, 06 February 2024 - 06:49 PM.

[brionl]

What are heat plumes? I’ll be in a parking lot in the Indianapolis area. It won’t be hot on April 8. I don’t understand this issue. Please explain. Thank you!

 

The asphalt gets hot, and heats up the air, which rises, in a very wibbly-wobbly manner usually.

[Sly2001]

Would that happen in early April in Indianapolis when the weather isn’t hot?

[kfiscus]

The question of whether the lights come on depends on each business and town.  Some will be on timers but more will be on light sensors.  They will come on right when you don't want them to.

 

The heat bloom effect can occur regardless of temperature because the sun will be warming pavement at a faster rate than grass and other natural surfaces.  If it is clear (which is what everyone is hoping for), the sun will cause some turbulent seeing above pavement and roofing.

[CreatorsHand]

Would that happen in early April in Indianapolis when the weather isn’t hot?

It depends on what you consider hot. Looking back through historical records for Indianapolis, while the average high is in the low 60s, there were 10 days in the last 13 years between April 6th and April 10th that were at least 74 degrees and as much as 85 degrees; even more if you add a few days on either side. That is warm enough on a clear day to put up significant heat plumes from asphalt and roofs of buildings. If I was going to shoot from a parking lot, I would try to find a spot on the South side where you weren't looking over asphalt or a building looking between South and West-Southwest.

 

Paul

[Sly2001]

I’m not going to shoot/image/photograph. I just want to know if the heat plume issue could effect how the corona appears through my binoculars.

I saw lots of videos of people watching the 2017 totality in parking lots, and that was in August.

Thanks again for answering my questions!

Edited by Sly2001, 07 February 2024 - 11:49 AM.

[Cajundaddy]

What are heat plumes? I’ll be in a parking lot in the Indianapolis area. It won’t be hot on April 8. I don’t understand this issue. Please explain. Thank you!

Heat plumes are air turbulence caused over surfaces that are significantly warmer than the ambient air temperature.  Asphalt, concrete, and roofing are well known to be 30*F warmer than the surrounding air temp at mid day causing turbulent heat plumes (distorted) viewing with binoculars, telescopes, and camera lenses.  The higher the magnification, the greater the image distortion.  These are the reasons that experienced observers prefer to be near water or over grass.  Those surfaces tend to be much closer to ambient temp at mid-day and tend to generate stable air with very little heat plume effects.  It is the temperature delta, not so much the ambient air temp for the day that matters most.  In full mid-day sun with air temp @ 50*, the asphalt will likely be 80-90*F and generating heat plumes.

I don't know what the temp delta over asphalt will be for you on the afternoon of the eclipse but it will probably be 30* higher than over grass.  Will it matter to you?  Only you can decide.  I suspect that the heat plume effect would be a lot greater than the distraction of street lights coming on during totality though. 

A few measurements on a 78* afternoon:
​https://www.thebaref...threshold.6527/

Edited by Cajundaddy, 07 February 2024 - 03:49 PM.

[Sly2001]

So if I stand on grass near a parking lot, would that avoid the heat plume issue, or do I need to be far away from a concrete surface?

The reason I ask is because I plan to be in the south suburbs of Indianapolis along I-65.

Thanks again!

Edited by Sly2001, 07 February 2024 - 08:53 PM.

[CreatorsHand]

So if I stand on grass near a parking lot, would that avoid the heat plume issue, or do I need to be far away from a concrete surface?

The reason I ask is because I plan to be in the south suburbs of Indianapolis along I-65.

Thanks again!

It depends on how large the grass area is and where it is in relationship to a parking lot or road. You will likely be looking just West of South at the beginning, and just West of Southwest at the end of the eclipse; if you are looking over a parking lot or road or the roofs of buildings anywhere in those directions, it could still affect your view even if you are standing on grass. If you look over a large parking lot on a hot day, you can see the heat plumes distort the view of whatever is in the distance.

 

Paul

[Sly2001]

Would the temperature drop that accompanies totality mitigate the heat plume issue?

Edited by Sly2001, 09 February 2024 - 10:02 AM.

[CreatorsHand]

Would the temperature drop that accompanies totality mitigate the heat plume issue?

It likely will to some extent, but it takes a while for all the heat to come out of asphalt and building roofs; do you want to gamble that it does on what may be your only chance to see a total solar eclipse? If you aren't going to photograph it, maybe it won't matter, and maybe you won't mind if the view ripples a little bit. If it were me, I would be spending time on Google Maps looking for a spot that is looking over as much grass as possible to give myself the best chance of a good view as possible, as well as several backup spots in case you can't find a place to park, unless you have control of where you plan to be. I would also make sure I was on the South side of the highway.

[Sly2001]

I’m not going to photograph. I will be using 8x42 binoculars to view the corona. How drastically could my view be effected?

Edited by Sly2001, 09 February 2024 - 12:10 PM.

[Cajundaddy]

No way to know this.  The only thing that is certain is that views will ALWAYS be best over water or a large grassy sports field or park.

Clear skies!

[sbsbbugsy]

In 2017, I could see the light come on along Interstate 80 and in the town of York Nebraska from my RV park.