Alun Richardson - Rucksack Guide--Winter Mountaineering

Winter Mountaineering is the fourth book in the Rucksack Guide series and covers the skills required to become a competent winter mountaineer. This handy book can be kept in your rucksack and will help you to gain the experience to mountaineer safely in winter anywhere in the world. It does not cover the technical aspects of navigation or alpinism (see Rucksack Guides to Mountain Walking and Trekking and Alpinism).

The Rucksack Guide series tells you what to do in a situation, but it does not always explain why. If you want more information behind the decisions in these books, go to Mountaineering: The Essential Skills for Mountaineers and Climbers by Alun Richardson (A&C Black, 2008).

For more information about the author, his photographs and the courses he runs go to:

www.alunrichardson.co.uk.

On a cold clear day, with firm snow, winter mountaineering can be safer than in summer. However, it can all change in a few hours and gale force winds, blizzards, zero visibility, avalanches and the numbing cold will soon sap your reserves.

Winter starts as the sun drops on the horizon and the Earth is warmed less effectively. In the Northern Hemisphere this allows the Polar Front to move south bringing colder air from the Arctic. From autumn, through winter and well into spring, the battle between the warmer moist air to the south, and the colder drier air to the north, produces the winter storms that bring the snow to the UK and North America. (See Mountaineering: The Essential Skills for Mountaineers and Climbers (A&C Black, 2008) or Rucksack Guide: Mountain Walking and Trekking (A&C Black, 2009) both by the author, for more information on how our weather is made).

The low pressure gradient within winter storms often creates strong winds of 160kph plus. Gusts of 70kph and above are difficult to walk in and the wind above 800m, especially in Scotland, is at least double the strength at sea level. The wind chill factor can make it feel even colder: +5C in a 50kph wind can feel like 12C on exposed flesh. The mountains in winter are serious places.

Aanoch Eagach traverse, Glencoe, Scotland

When the temperature of a cloud falls below 0C, tiny particles, such as bits of clay, encourage water to turn into ice crystals that then combine to form snowflakes.

A snowflake is a number of snow crystals that join together as they fall through air that is close to freezing. When the temperature is ideal for stickiness, and the wind is light enough not to break them up, the flakes can grow very large.

Varying temperature, moisture and wind conditions favour crystal growth in different ways ():

Stellar crystals (1) The classic star-shaped snowflake

Columns (2) New snow crystals in a six-sided hollow or solid prism

Needles (3) Long, thin forms

Plates (4) Thin, usually hexagonal crystals

Graupel Soft hail created by water droplets that freeze to crystals forming round particles

Ice pellets Form when rain falls through a very cold air mass