There is a really good attempt to give a flavour of the whole subject of natural navigation in an article in the Independent today by Tim Walker. Tim came for a walk in London to sample natural navigation urban-style.
Anyway, flower pot time. Take a look at this photo that I took yesterday just before lunch. Note the wet ground in the shade and how the shadow of the pot has moved ‘up’ leaving a wet area in its wake. The shadow is moving west to east, away from the camera. As it is close to the middle of the day, the sun is close to south and to the right of the picture. The shadow of the young tree is a near perfect north-south line.
There is also a shadow in the pot itself, on the right, southern side. This shade is allowing one side to stay moist longer than the other, northern, side. There is more moss close to the southern edge of the pot.