The natural Navigation: The Right Course, Naturally

One of the tricks of desert navigation is remembering that wind direction is never entirely random and over time is actually quite dependable. If we know the direction the wind normally blows from and we have ways of reading that direction from the land then we can get our bearings, even when there is no wind at all.

If you are interested in the relationships between wind, sand and desert then there is a good introduction on this page from the Earth Science Australia website. It includes explanations of the great-sounding parabolic, star and barchan dunes and the even better sounding ‘Yardangs’.

There was a typically excellent Horizon documentary on BBC2 last night called, ‘Do You Know What Time It Is?‘ It ranged and veered in a challenging and entertaining way from the Mayans to the sub-atomic. I hadn’t planned to watch it all, more of a ‘give it a chance’ type of sit down, but it got its claws in early on. I failed to escape the sofa for the full hour, despite being subjected to some string theory along the way.

One of the things I learned (as opposed to being ‘bamboozled by’) was that the time it takes the earth to rotate varies slightly (a millisecond or so) each day and the reason for it is… the winds. The winds on earth actually affect the speed the whole thing rotates. And, as Columbo might say, one more thing… the speed of the earth’s rotation is slowing down, a…

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A little over a month ago I promised to look at how trees have brown or ‘tanned’ looking lichen on their north side in this country (even though buildings tend to have brown mosses and lichens on their south side). This silver birch is a good example of how striking that rusty brown colour can be. It has a strong bias towards growing on the north sides of trees in England. The only reason I have for that is a likely preference for moist conditions. Lichens are wonderfully complex organisms. Any plant or animal is likely to have hidden depths and take time to fully comprehend, but lichens take this to a new level. In a conversation with Rob, the local Forestry Commission manager, he was quite candid:

‘Yes, I’ve noticed that growth too, but to be honest if you want to know more you need to talk to…

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During a navigation exercise in the South Downs last week, I ducked under an arch formed by a large fallen beech and then got stuck. When I finally managed to extricate myself I found this beast that had locked itself into my rucksack. It was lucky that it was my pack not my back that caught it or there would still be part of me out there.