(Note that all my comments are Nothern Hemisphere centered, 40[sup]o[/sup]N specific. No offense meant to our fellow Dopers “down under”.)
What I’ve said is that in the spring & summer, the Sun’s path is sometimes in the northern half of the sky and sometimes in the southern half. It’s in the northern half just after sunrise and just before sunset, with the “just” amount varying from 3.5 hours at solstice to infintesimal close to the equinoxes. But its path crosses from north to south and vice versa hours before “noon”, i.e. when the Sun is at its highest.
The 23.5[sup]o[/sup] measurement is in no way related to how high the Sun gets in the sky. It is the degree of tilt of the Earth relative to the plane of the solar system. What it does define is the range of latitude north and south that the Sun can be overhead, 23.5[sup]o[/sup] north and south of the Equator.
On an equinox at noon, the Sun’s elevation (degree measurement from the horizon) is easily determined from a given location’s latitude: 90[sup]o[/sup] - latitude. So at the equator, the Sun’s noontime elevation is 90[sup]o[/sup]; in DC its elevation is 51.2[sup]o[/sup], and at the North and South Poles its elevation is 0[sup]o[/sup]. (Yes, the Sun is right at the horizon all day long on the equinoxes at the poles.) At Summer Solstice, these elevations vary by 23.5[sup]o[/sup]: the equator Sun’s elevation is 66.5[sup]o[/sup]; in DC it’s 74.7[sup]o[/sup] (just about following what I determined earlier sans mathematics); and at the North Pole it gets up to 23.5[sup]o[/sup]. (At the south, we’d subtract, getting -23.5[sup]o[/sup], which means of course that the Sun never rises above the horizon at the South Pole near the June Solstice.)
Sorry I can’t explain things easier. Maybe if I have time later I’ll post some pictures of how this whole thing works.
Umm just don’t get it; aren’t the 74.7 degrees measured up in a straight line from the south? Yes, the sun is further north than it will be at any other time, but relative to Jon Doe in Washington D.C., isn’t the sun 74.7 degrees above the southern horizon, which would still be south?
I downloaded and looked at a GeoClock - one with the time zones and sunlight, etc. and I still really don’t get how the sun would ever appear to be in the northern sky for someone that lives north of the tropics.
At celestial noon (when the Sun is due south and at its highest elevation for the day), the Sun is indeed at 74.7[sup]o[/sup] above the horizon measured from the southern horizon. But the path that the Sun takes through the day is not “perpendicular” to the Earth’s plane, it is tilted. Because of this tilt, part of the path is in the southern sky, part in the northern. I’ll try to draw a picture and post it.
But isn’t the sun the highest in the sky that it will ever get that 74.7 degrees? Wouldn’t that figure have to be > 90 to appear to be out of the northern sky?
If what your saying is so, this will make one damn good bar bet…
This sounds like the best bit of practical advice I’ve seen in this thread. I’d like to underscore it, and add an observation. When I first did some caving many years back, I was always reminded to look back, because passage would look radically different when you were returning than when you were going in. This is a learned skill for nearly everybody. This isn’t always practical in driving, but perhaps you DO want to conciously look back the way you came when you make a turn, in order to fix the appearance coming back the other way in your mind. If you can do so safely, of course. You can certainly do that as you pull into a parking lot, and note what the street looks like in the correct direction to turn when you pull out.
This is also true in the world of backcountry travel. I didn’t remember that at the time of my original post. It becomes an unconscious habit.
One other note. If you should happen to become lost, Stop. An extra 5 minutes won’t make a significant impact on your schedule. Continuing your journey may make matters worse. Think about where you are. When were you last sure about your location? Consult your map and make an educated guess about your location based on the last prominent landmark, direction of travel, and the time it took. That should help you retrace your steps.
Correct in that the 74.7[sup]o[/sup] is the highest elevation that the Sun will attain at the latitude of Washington, DC.
Incorrect in how elevation is measured throughout the day. The elevation is measured along the azimuth (direction) that the Sun is from the observer, not from the due south line. For example, in the data I showed above, at 09:21 am the Sun’s azimuth is 90.00[sup]o[/sup], and its elevation is 39.51[sup]o[/sup] along that line. A way to think of azimuth is the direction opposite of the direction that your shadow is cast. Therefore, at 9:21 on 6/22/01 in DC, shadows will be cast due west of the objects casting them.
90[sup]o[/sup] is the highest elevation possible, straight above the observer. There can’t be elevations higher; what you would really have is a smaller elevation measurement in the opposite direction.
(I have a couple of perfect pictures to illustrate this. Unfortunately, my free webserver is having programming problems and I can’t upload them. I’ll let you know as soon as I can.)
Thanks for the responses, especially yabob and ianzin. Very insightful.
I still wonder if people who have a “good innate sense of direction” actually take notes subconsciously (gas station on the right…big “Coke” billboard…funny looking tree…) or do they have something else going on? I have friends who can (literally) find their way around in the desert, where all the cactii look identical. Are they subconsciously taking bearings based on the angle of the sun? You are right that I often do not take a conscious interest in my surroundings -
One thing is for sure - I am much better at remembering wordy things than physical/spatial things. I often do exactly what ianzin suggested - memorize directions verbally. That is a problem though if I miss a turning or deviate one iota from the memorized route!
I think I’ve read that there are two sorts of people with good senses of direction - those who have a map in their head and those who memorize a list of the things they passed and places they turned.
Umm just don’t get it; aren’t the 74.7 degrees measured up in a straight line from the south? Yes, the sun is further north than it will be at any other time, but relative to Jon Doe in Washington D.C., isn’t the sun 74.7 degrees above the southern horizon, which would still be south?