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On a sunny day, one can find the direction (NESW) by observing the Sun's movement across the sky.

In the northern hemisphere, during a clear night, one can find the direction by looking at Polaris or other stars and constellations.

However, how can one know the correct direction during a cloudy day/night without using any gadget such as a compass, the Internet, or a watch?

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    $\begingroup$ How is this not duplicate? $\endgroup$ Jun 30, 2023 at 10:44
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    $\begingroup$ @PeterMortensen of? $\endgroup$ Jun 30, 2023 at 11:55
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    $\begingroup$ @JeopardyTempest, maybe Columbus $\endgroup$
    – osiris
    Jun 30, 2023 at 16:11

7 Answers 7

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The book Finding Your Way Without Map or Compass by Harold Gatty (Goodreads review) is well worth a read if you're interested in this sort of thing. The chapters Reflections in the Sky and Directions from the Wind are particularly relevant

It includes more accurate ways of solar navigation, tips about moss on trees, and many others.

Wind

If you know the dominant* wind direction in open country, isolated trees will lean away from it. This is obvious on Dartmoor (an upland area in Southern England I know well) for example. This works less well in valleys that affect the local wind direction. In mid-latitudes the prevailing wind is usually broadly from the west, but SW is a better estimate round here.

Lone Tree near Combestone Tor,  Dartmoor, England.   Jeffrey Pardoen, cc-by-2.0 via Wikimedia Commons

Lone Tree near Combestone Tor, Dartmoor, England. Jeffrey Pardoen, cc-by-2.0 via Wikimedia Commons

Again, using the prevailing wind, airport runways are often aligned to it - but paved ones have their direction painted on them anyway; even grass strips are likely to have some indication if they have any infrastructure at all.

Orientation to the sun

Old factory buildings (predating cheap electric lighting), where they survive, often have northlights forming a saw-tooth roof (Wikipedia) - the (near-)vertical panes face away from the equator.

A more modern variation on that is solar panels - they will face towards the sun. If sited freely on the ground, they will face S in the northern hemisphere. Rooftop panels will usually face more S than N (again in the northern hemisphere) but are constrained by the roof angle.

Returning to trees, many species show greater growth on the sunward side, with longer, flatter, branches

If you have a map, even a basic or mental one, but no compass

This is becoming less common as mapping is increasingly electronic, but with a map but no compass, there are things you can do.

In the dark, the lights of towns reflect off the clouds, giving you the direction towards them even if they're the other side of a hill. Or in Gatty's words:

On land an overcast sky can signal signal many different things to the traveler. One of the simplest and most important of these things is the well-lit human city, town, airfield beacon, or even powerful lighthouse. The loom of these lights in the sky can often be seen when their source is below the observer's horizon.

Near the coast, you can often tell which way the sea is even if you can't see it. Gatty goes into more detail, but if in one direction there are clearly no hills behind the closest few, that will mean the sea (or a plain). Sea birds can help here too.

Of course if you know where you are, and there's a distinctive peak or similar feature on the map and visible, you can orient the map to that. In that case even a mental map and knowledge of the area can help. I know there's a radio mast called Mendip, as the eastern end of those hills. That's enough to get my bearings if it's within sight, combined with knowing the terrain I'm in (if it's not hidden by cloud of course). On Dartmoor I can recognise some of the hills, and know roughly how they relate to each other. There I'd have a paper map, so even if my phone battery died and I lost my compass, that would be enough for navigation if the cloudbase was above the hills.

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* I originally wrote "prevailing wind", but on re-reading Gatty this weekend I realised that was a slight error or inconsistency : he defines the dominant wind in a way that takes into account the strength as well as the frequency for a direction - a weighted average, while the prevailing wind only considers the frequency. In many areas they will be similar enough to make no difference for our purposes.

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    $\begingroup$ Re-reading Gatty at the weekend, I realised that some of the language is a little dated (after all he was writing in the 1940s and 50s), but it's aged pretty well. The title I give is that of the 1999 reprint of the original 1958 Nature Is Your Guide. $\endgroup$
    – Chris H
    Jul 3, 2023 at 10:14
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    $\begingroup$ While I've concentrated on land-based methods as they're what I've paid attention to, there are equivalents at sea, but for those it's worth reading the book. $\endgroup$
    – Chris H
    Jul 3, 2023 at 10:16
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The first thing that can be done is to wait for sunrise of sunset. These will give the direction of east and west. Even during overcast conditions one side of the sky will be illuminated and the opposite side will be much darker.

During an overcast day, one can use a tool the Vikings used, sunstones, also known as birefringent calcite sunstones.

Another method for finding north or south is to look at the trunks of old trees. Moss can sometimes grown on the side of the tree shaded from the sun. In the northern hemisphere that would be the northern side and similarly in the southern hemisphere that would be the southern side.

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    $\begingroup$ The moss thing is complicated by it also growing on the wetter side. Here in the south of the UK, our (especially wet) winds come from the SW and what sun we have mainly from the S. So the effects are in competition $\endgroup$
    – Chris H
    Jun 30, 2023 at 8:56
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    $\begingroup$ Moss is one of those things that works better in theory than in practice. I tried doing it once, and went in a generally northerly direction overall, but at various times I was going in every direction including due south. $\endgroup$
    – Mark
    Jul 1, 2023 at 3:34
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This requires some preparation, but if you know the weather forecast and it predicted a steady wind from a certain direction, it's easy to identify that direction.

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    $\begingroup$ A fair answer... though indeed it can be noted that there are certainly enough days without a very steady wind at all to use... plus factors like topography and localized features [buildings, trees, small scale features like thunderstorms, etc] (as well as in general just plain variability, especially on days that aren't that strong of wind overall) can alter it of course quite a bit, leaving it less than a reliable lock, even on many decent days. But every bit helps if needing to know direction, so this definitely helps!+1 $\endgroup$ Jun 30, 2023 at 8:37
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In cities, I actually look for satellite dishes. They are always directed towards the equator, in Germany usually mostly South, slightly East.

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    $\begingroup$ Could you please tell the reason behind it? $\endgroup$
    – YYY
    Jul 1, 2023 at 21:42
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    $\begingroup$ @YYY Communications satellites are generally geostationary - i.e. their orbit around the earth takes 24 hours, meaning that they appear to be stationary in the sky. This only works if the orbit is in the plane of the equator - otherwise the satellite would drift across the sky, until eventually your TV signal would get lost when it moves out of line-of-sight of the antenna. $\endgroup$ Jul 2, 2023 at 0:32
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You don't have a compass? Build one!

This solution still requires you to have a needle though... But it's often included in first aid kits.

  • Put some water in a small pool, or in a cup
  • Put a leaf in the water
  • Rub the needle against your clothes
  • Put the needle on the leaf

The leaf will turn on the water until the needle's thicker end points to the north.

Note that contrary to a map, a GPS, or even Polaris, this solution will give you the magnetic north, not the "true" or geographic north.

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    $\begingroup$ I remember trying this as a kid, and it didn't seem as easy to do as it was suggested to be. Would you agree that it takes at least extreme care, or perhaps a bit more expertise/experience? $\endgroup$ Jul 1, 2023 at 0:36
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    $\begingroup$ I don't understand the "Rub the needle against your clothes" part. If the needle is magnetic, this isn't needed, but if the needle isn't magnetic, how will that magnetize it? As the needle is (presumably) metallic, there won't be a buildup of static electricity. $\endgroup$ Jul 3, 2023 at 5:41
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    $\begingroup$ @JeopardyTempest Honestly, I don't know: my own memory as a kid was 30 years ago... I just remember being amazed at the moving leaf! :) $\endgroup$ Jul 6, 2023 at 13:01
  • $\begingroup$ @GuntramBlohm Not sure... I found someone claiming that it can work with a pine needle, in that case charging it would be necessary, but maybe not with a metallic one, you're right. $\endgroup$ Jul 6, 2023 at 13:02
  • $\begingroup$ This has been discussed at Physics.SE where it couldn't be replicated (@GuntramBlohm) $\endgroup$
    – Chris H
    Aug 15, 2023 at 14:42
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Look for moss, mildew and algae on trees, rocks, etc. Even houses.

In the Northern Hemisphere, the Sun arcs across the southern sky. All that sunshine on the south side of such objects reduces moisture, which is not conducive to the growth of such plants.

The northern side, though, in constant shadow, retains more moisture and therefor moss, mildew, etc grows.

This in only a generality, though, since for example, the north face of a mountain will have less sun anyway.

It's the exact opposite in the Southern hemisphere.

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big props to the other replies. this only works in some instances: If it is cloudy and there is the slightest hint of radiant direcionality, you can prod a straight stick on white piece of paper and there can be enough shade to see where the sun is.

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    $\begingroup$ Gatty proposes a refinement of this. Using a knife or other thin item (ruler?) rather than a stick, you rotate it, and when the shadow is at it's narrowest, the blade is aligned to the sun. That's a bit more precise, when you consider how broad and fuzzy a shadow can be on an overcast day $\endgroup$
    – Chris H
    Aug 15, 2023 at 14:35
  • $\begingroup$ Yes, it helps to have a plain piece of paper too. indeed a knife/ruler would be good if available. $\endgroup$ Aug 23, 2023 at 15:46

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