BRC sun/wind direction map?

[sadie]

Maths, schmaths! The answer is a gigantic lazy susan under your entire set up.
Of course there is the risk of high winds turning you into a playground whirly-gig.
Perhaps a DaVinci style cog/lever lazy susan should be considered.

[lucky420]

Maths, schmaths! The answer is a gigantic lazy susan under your entire set up.
Of course there is the risk of high winds turning you into a playground whirly-gig.
Perhaps a DaVinci style cog/lever lazy susan should be considered.

+1000

[mrchiff]

The simple method is to just point your door/entry towards the sunrise.

[Jackass]

I started putting a compass in my truck after too many times of setting up camp, only to find out in the morning that I'm right in the sun... I usually arrive at dusk or after dark where ever I'm camping. Now the first thing I do is bust out the compass to figure out where east is, and either put the back wall of my trailer facing that way or set up directly west of a tree's trunk if I can't get under it. Compasses are useful for more than just finding your way. Phone compasses will lie sometimes for whatever reason and magnetic compasses will lie sometimes if you are in or around your vehicle or trailer (metal).

[Token]

Sorry Zig, to align with opening, go

103 - 90 = 13 degrees off true north.

Sometimes us geeks just ramble with assumptions. My bad.

If you have a choice of 4:30 to ~ 6:00, setting up at 4:30 lets you just point the opening towards the man and be done with it. Length of hut parallel to radial.

4:30 statistically has a bit less dust as well. Increases as you go towards the 9:00 side on the clock. Mind you, statistically only. Any given year can go whichever way.

[jasonk]

If you have a choice of 4:30 to ~ 6:00, setting up at 4:30 lets you just point the opening towards the man and be done with it.

I'm confused. If you're at 4:30, pointing towards The Man, isn't that north? (is that true north or magnetic north?)

I still don't understand why 103 is the magic angle. It neither bisects the 6am/8pm sun-line (to equalize shade all day), nor is it at right angles to the 6am sun-line (which would maximize morning shade)

[Token]

I'm confused. If you're at 4:30, pointing towards The Man, isn't that north? (is that true north or magnetic north?)

It is North-ish, simply because we are lazy to look this up for you exactly and do not have all the data from the Survey Team that lined up the streets and radials.

If you absolutely need that much precision, go here and immerse yourself into the GPS data.

http://www.wkeller.net/BRC-GPS/

I still don't understand why 103 is the magic angle. It neither bisects the 6am/8pm sun-line (to equalize shade all day), nor is it at right angles to the 6am sun-line (which would maximize morning shade)

Took the sun-set position, subtracted sun-rise position = 206 degree arc
Divide that by 2 = 103 degree arc to zenith

77 degrees + 103 degree arc to zenith = 180 which is South - The ass end of the hut

Hence point the hut "door" side north + ~13 degrees for the magnetic drift of a compass...

...Or roughly the 4:30 radial.

[Skuzzy61]

103 degrees is the center of the arc the Sun travels from sunrise to sunset. It occurs at about 1:00pm (time). The arc only varies about +-2 degrees as the Sun travels from E (-2 degrees) to W (+2 degrees).

At 1:00pm (time), If you are standing at 4:30 (location) in BRC, and looking at the man. The Sun will be positioned directly overhead and approximately 32 degrees behind you (draw a line to the sky perpendicular to your location and then an arc of 32 degrees from that) moving from your right to your left. This happens to also be the highest Sun elevation (i.e. the shadows will be their shortest).

I do not have time to do a 3D representation of this. I wish I did as it would be much easier to understand.

Armed with this data, you should be able to ascertain the orientation of whatever you are going to be living in in order to minimize Sun exposure, assuming that is a priority.

By the way, all these numbers are based on the longitude and latitude of BRC, and on August 28.

I hope that is helpful.

[BBadger]

Took the sun-set position, subtracted sun-rise position = 206 degree arc
Divide that by 2 = 103 degree arc to zenith

103 degrees is the center of the arc the Sun travels from sunrise to sunset. It occurs at about 1:00pm (time). The arc only varies about +-2 degrees as the Sun travels from E (-2 degrees) to W (+2 degrees).

Is that 103 degree figure correct? Why does it employ a subtraction operation? Shouldn't the center of the arc be at 180 degrees from North, the average of the two angles, (283 + 77) / 2 = 180 degrees? Even on the table posted above, the azimuth for 1:00 PM is at 180 degrees.

77 degrees + 103 degree arc to zenith = 180 which is South - The ass end of the hut

Doesn't this mean that 180 degrees is the angle you're now shooting for? The 103 degrees only orients you towards the sunrise angle. It doesn't have any correspondence with maximum intensity.

I think to calculate maximum shade (not necessarily optimal), we need to do a horizontal shade calculation as well as a vertical shade calculation for the geometry of the structure, following something like this.

I do think 103 degrees, or somewhere around there is a good angle for blocking out most of the effects of morning sun, but as far as maximizing shade in the absolute I'm not convinced these calculations above are correct. If I'm wrong, I'd like to know where these calculations are coming from.

[Token]

Sun rises at ~ 77 deg
Sun sets at ~ 283 deg

Sun travels 206 degrees across the sky

Mid point of travel is 103 degrees, or in reference to North that is the starting point of 77 plus the 103 travelled.

So zenith (i.e. Apex, highest point in sky) is at 180 (77+103) as referenced by true North.

So a monkey hut will provide the most shade over the course of the day if you park the ass end toward the zenith, in this case that is exactly South.

Any more and I gotta draw it.

[BBadger]

So then that 103 on the map above is wrong for max shade in this absolute sense, as it is 103 degrees degrees from due North, instead of the azimuth at dawn at 77 degrees. All we really wanted was pointing south at 180 degrees from North.

I think the confusing part is that instructions refer to "103 degrees" without mentioning the 0-angle reference point. It'd be less confusing to just state "align it North-South to block out the side-sun". It's also seems like a lot of extra work, as one has to first wait until sunrise/sunset to obtain a bearing on the position of the sun, and then add some oddball angles together based on the time of year just to get the south bearing. I guess maybe if you're lost in a forest it's great, but for a car-camping place like BM the instructions should really be: "find North with a compass and align your shit North/South."

I'm still going to aim my walls towards 9:00 to block out the morning sun. Maybe when it's not crunch time I'll run the numbers and see what is the actual optimal angle for a shade structure like a MH or just a box with open ends.

[Skuzzy61]

Alignment will depend on the structure. For instance, I am lining our RV up E/W (slightly tilted so the W Sun position will not make contact with the awning side of the RV) with the cockpit pointing W. Why? To minimize the area of exposure to direct sunlight. All the glass will be covered with Reflectix, so no matter what time of day it will always be dark in the RV.

This alignment also extends the shade on the side of the RV with the awning.

Now, it also means we will have some Sun to deal with, under the awning in the early and late daytime hours, but that is the tradeoff in order to help keep the interior of the RV cooler, longer. If everything I have read is accurate, about the Onan generator in the RV, we will only be able to use it about 4 hours a day, due to limited fuel (we are going to be on the Playa for 9.5 days).

A different type of structure will have different requirements. Everyone has to set their priorities.

BBadger, when you express Sun elevation and azimuth, the elevation is the number of degrees above the horizon. The azimuth is traditionally expressed as degrees clockwise from N. Any point of the arc can be expressed as degrees from N (180 for the zenith), or as relative to the origin (sunrise) (103 for the zenith) which can be easily measured with a protractor.

[Token]

Oh Snap, now I get it Badger.

You edited a map and posted it with an absolute - 103 to North set of arrows.

Sorry, I just re-scanned the thread and figured that out.

Yeah, the drawing is good for all the arrows and times, just that 103 absolute is superfluous. Means nothing.

The 103 degrees is in reference to sunrise, not North.

See, crayons do help.

Sorry, my bad.

The 103 as marked in the drawing is not very interesting. 180 is interesting.

[Skuzzy61]

I would be a horrible teacher. I just lack the ability to explain things well.

How about this? (yes, he is tenacious)

Simply stand up, anywhere, in BRC, and look due North @ 7:00AM.
Using a compass, turn and face 83.18° (Azimuth), clockwise from North.
Now, using a protractor, tilt your head up 6.53° (Elevation).
You will now be looking at the center of the Sun (uh,.don't really do it).

Take any time of the day off my chart and repeat the above.

Armed with that, anyone should be able to decide the exact orientation of their camp.

[BBadger]

Thanks Token, it makes more sense to me now.

I might just leave it as is as it blocks most of the morning sun which I think is probably sufficient for most people.

Skuzzy61: Instead of relying on getting/stating up to 7AM, bringing along a protractor, and working with an angle that has four significant digits, I think I'll just rely on a regular compass.

[Canoe]

Here's the map for 2016 using the 2016 BRC layout. Somewhat easier to locate your camp and its orientation.
Lat&long of Man from Google maps (40.7842516, -119.2007847).

BRC sun track - 2016-08-28.gif

If you've got a camp layout done (and you know were North will be), you should be able to put this transparent gif on top to see how the sun lines up to your camp.

BRC sun headings - 2016-08-28.gif

To check how much ground your shade will cover.
Shadow Rule of Thumb (foot): for every foot high, an object casts a shadow of:

• At solar noon (12:57), ~2/3 of a foot,
• 11am & 3pm, almost one foot,
• 10am & 4pm, just shy of one & 1/4 foot,
• 9am & 5pm, somewhat more than one & 3/4 foot,
• 8am & 6 pm, almost three and 1/4 feet.

[jasonk]

Here is a table of Sun elevations (Elevation measured in degrees above the horizon) based on the hour of the day.
Date: August 28, 2016 (GMT-8)
coordinates: 40.7886448, -119.2030177
location: Black Rock City, Nevada, USA
hour Elevation Azimuth
6:20:25 -0.833° 76.76°
7:00:00 6.53° 83.18°

This is cool data, where did you get it from?

[Canoe]

http://www.sunearthtools.com/dp/tools/pos_sun.php

[Token]

Smashing Good.

+1 Jedi point for Canoe

[Canoe]

+1 Jedi point for Canoe

Thanks
Pain in ass setting every single line to the exact angle.
And it does differ based on the lat&long of BRC's position on the playa.

[Skuzzy61]

Here is a table of Sun elevations (Elevation measured in degrees above the horizon) based on the hour of the day.
Date: August 28, 2016 (GMT-8)
coordinates: 40.7886448, -119.2030177
location: Black Rock City, Nevada, USA
hour Elevation Azimuth
6:20:25 -0.833° 76.76°
7:00:00 6.53° 83.18°

This is cool data, where did you get it from?

You can find it at several sites. Canoe got one of them.

[PL_FL]

Here's the map for 2016 using the 2016 BRC layout. Somewhat easier to locate your camp and its orientation.
Lat&long of Man from Google maps (40.7842516, -119.2007847).

THANKS! And yes, intuitively, 'just point your shady side a little south of due east' ... At least that's my plan

[Canoe]

Just checked the data for 2017-08-28.
The angles are within a quarter of a degree and 15 seconds of the 2016 map.
Sunrise/set go from

• 2016 6:20:25 & 19:34:30 to
• 2017 6:20:12 & 19:34:55.

So the sun/shadow angles and times are extremely close to the 2016 maps. You may rely upon the angles & times.
Confirming orientation of the city isn't possible until the 2017 map is out.

Once the 2017 Black Rock City map is out and its precise location known, I can do any possible corrections and the overlay.

Here's the map for 2016 using the 2016 BRC layout. Somewhat easier to locate your camp and its orientation.
Lat&long of Man from Google maps (40.7842516, -119.2007847).

BRC sun track - 2016-08-28.gif

If you've got a camp layout done (and you know were North will be), you should be able to put this transparent gif on top to see how the sun lines up to your camp.

BRC sun headings - 2016-08-28.gif

To check how much ground your shade will cover.
Shadow Rule of Thumb (foot): for every foot high, an object casts a shadow of:

• At solar noon (12:57), ~2/3 of a foot,
• 11am & 3pm, almost one foot,
• 10am & 4pm, just shy of one & 1/4 foot,
• 9am & 5pm, somewhat more than one & 3/4 foot,
• 8am & 6 pm, almost three and 1/4 feet.

[Canoe]

Updated with the 2017 map underlay.

BRC sun - 2017 - sun & city.gif

NOTE: BRC 2017 We are returning to our historic no driving, no parking, and no camping across L from 5:00 to 10:00 streets.

[Canoe]

2017 Sun Elevation and Shadow Ratios

BRC sun - 2017 - elevation & shadow ratio.gif

[EGAZ]

Thanks Canoe!

[Roundabout]

Thanks Canoe!
Is it just my eyes, or is your overlayed North arrow pointing at a slightly different angle than the BRC North arrow?

[Canoe]

Thanks Canoe!
Is it just my eyes, or is your overlayed North arrow pointing at a slightly different angle than the BRC North arrow?

I thought you'd be right, but I checked and both are (by the grid in Libre Office Draw) pointing exactly straight up (as is 4:30 street).

It could be an illusion as the black/white centre line of of the city N arrow is offset from the black edge of the stem, but more likely due to the road from the airport up to the end of 5:00 street doesn't run due north, but distinctly a tiny bit to the west (at least as it's drawn). But it's even more likely due to the fact that solar noon is NOT at 1pm (~12:57) so the 1pm sun line is not exactly down 4:30 street, but slightly clockwise of it. This also means that the fan of on-the-hour sun lines are not symmetrical to, nor equally spaced from, the hours of the streets. So the whole alignment looks/feels slightly off.

[Canoe]

If you want a real mental mismatch, the shadow angle & length posted above is the distance from the base In The Direction Of The Shadow, not the distance out towards North from the base. So I plotted the shadow cast by an 8' long by 8' high wall running exactly East-West. My mind can't reconcile the two.

BRC sun shadow example- 2017.gif