Today’s guest post is from Simon Shanks – an experienced runner, hill walker and graduate of Royal Marines Commando Training!
One of the most rewarding things about being on the hills can be the spectacular views (weather conditions permitting!). Something else you may have noticed, which can be just as spectacular, is the weather-induced phenomena. You may well have seen these formation and wondered what they were – from footprints sticking up above the snow, ice building up on fence posts into the wind to a temperature inversion. Here are 5 of the most common incredible weather formations to look out for when hiking and what causes them.
1. Rime Ice
This is where the moisture in the air, which is being blown along on the wind, forms as ice on a fence post, or anything else. It then builds up as more moisture freezes on top of it. This results in finger like ice crystals pointing in the direction the wind is coming from. This one is very common and easy to spot on any windy day when there is snow on the ground. If the conditions are right and have been for some time, the results can be spectacular.
2. Hoar Frost
This one requires there to be no wind. However it must still be cold. Frost forms on the surface of everything, including clothing. It is like a frozen layer of dew. Any wind and the effect will be blown away. Once back at the car, and your clothing heats up, it melts and you become suddenly drenched!
3. Raised Footprints
I have always liked this one, but when first seen it can be a bit puzzling. Imagine a heavy snowfall on the hills. A person then walks up that hill, their feet sink into the snow, compressing it underneath. Over the coming days and weeks the wind blows the loose snow on top away, gradually exposing the compressed footprints underneath. Eventually the top 12 inches or so of snow are blown away, deposited elsewhere, leaving the previously hidden footprints as the highest points on the ground. The imprints of the boots still very clear, and bizarrely, sticking up proud of the wind blasted floor.
4. Temperature Inversion
This one is dependant on your luck as the conditions must be ideal. I’ve been fortunate enough to see this a few times. This is where warm air moves in over cold ground. It normally occurs when a warm front rolls in after a prolonged cold period and the ground is so cold that it compresses the warm air above it forming fog. If the geography of the hill suits, you can actually walk through the fog and stand above it. It’s called an inversion because it’s actually gets warmer, the higher up you go. As the day goes on, the sun will burn off the fog, so it is best seen in the early morning.
5. Brocken Spectre
This one is the most bizarre and has also been blamed for Mountain Rescue call outs or indeed, the famous “Old Man of Ben Macdui”.
It occurs when walking downhill; the sun casts your shadow onto the clouds in front of you, ringed by a circular rainbow which forms as the light bends through the moisture, separating it into its individual colours. It has the effect of looking as if there is a giant person lurking in the mist ahead! Not very reassuring if you are walking alone!!!!
Got any pictures of your own? Share them with us!
Read more posts on hillwalking and hiking from Simon below:
Follow Simon on Twitter: @simonshanks1975