Storms and lightning - Rock climbing, via ferrata, hikes, ski

Storms and lightning

Let's talk a bit about thunder and lightning, which take place during storms and which of course are of much interest to climbers and mountaineers.
Storms typify the summer season, from June to September, during which period we can on average have 6-10 days with storms per month, usually in the afternoon and evenings. The coming of a storm can be forecast by observing the local weather conditions. For example, the cloud cover over the mountains can indicate the direction the storm will take. But sometimes the irregularity of the cloud formations means it’s not always possible to accurately predict if and where the storm will strike. More accurate predictions can result from counting the seconds between seeing a lightning flash and hearing the thunder.
An interval of 3 seconds between lightning and thunder means the storm is about 1,000 metres away.

On a plain, thunder can be heard up to 20 km away whereas in mountainous areas the sound is stopped from carrying by the high peaks. Echoes can however cause confusion over the violence of the storm. Without going into the details of storm electricity, we can say here that it is a friction electricity, or electricity generated by the friction of water droplets in contact with ice particles in the clouds, agitated by winds. The electrical discharges can be observed even before the rain starts to fall. The lightning hazard decreases when the sky is covered evenly by grey, rain-laden clouds.

The “fires” occur as bluish flames that arise from pointed metal objects, such as the crosses on mountain summits, electricity pylons etc.. Sometimes you can also hear crackling.
In the event of lightning hazard, you should move away from upward-pointing rocks and generally from everything that can act as a strike-point. Stay well away from cables, electricity pylons, trees or isolated rocks; avoid water- and drain-pipes, vertical walls and as far as possible keep away from metal objects.
Even sheltering under a rock is not a good idea, for electricity can spread down through the rock and still be dangerous. To sum up, although perhaps an obvious statement, we recommend you always try to find a shelter before the storm reaches you. Exactly what and where the shelter is depends on good sense.
The most serious hazard of storms is lightning, which is a discharge of electricity either among clouds, or between clouds and the ground. Lightning has a temperature of 30,000 Celsius and its speed is 10,000 km/sec.

The danger of impending lightning is heralded in these ways:
- exposed areas of the body feel a tickling sensation;
- goose pimples on the skin and hair standing on end;
- buzzing and small sounds emanating from metal objects;
- bluish flames ("Fuochi di Sant'Elmo") around particularly-exposed metal objects (e.g., poles, pylons, mountain summit crosses).

- move away from sheer rock faces and sit with feet together and knees bent up and held against the body;
- Always double check belays and back up your descending    device when abseiling (with a prusik , marchand, or similar).
- expanses of snow and glaciers are potentially safer than rocky areas;

- avoid herds of animals or groups of persons.


A special thank you to Ivor Coward, who translated this page.