Weather Summary

British hills & mountains are small but are very accessible. Every year, millions enjoy days or weeks walking, climbing and camping among the peaks; and every year, some people get into trouble. Some, indeed, are killed, because they went into the mountains unprepared for the weather they met. Some are unaware of the hazards of mountain weather; Some underestimate the risks; Some have rigid plans and do not change them due to the weather. Some leave decisions too late.

Why are we interested in it? Is it weather or climate? Rain – Snow – Cold – Wind – Sun Air Masses – High and Low pressure systems Forecasts Altitude AvalancheIsit

Weather As a mountain traveller we need to know;- What to wear What to carry with us Where to go, where not to go – winds! How high to go – temperature lapse rate! 1deg C / 100m dry air 1deg C / 200m wet air What is going to happen throughout the day or in the few hours after

Decisions There are emotive decisions and sound decisions based on facts

Choose Summer or Winter. Click on the arrows to find out more! Air masses

Hot air rises! Types of Rain

Convectional Rain

) The sun heats the earth. 2) The earth heats the air above it. 3) Hot air rises because it is less dense. 4) As the air rises, the water vapour in the air cools and condenses into water droplets. 5) A collection of these minute water droplets is known as a cloud. These minute water droplets join together, become heavy and fall as rain. Convectional rain

Relief rain

Frontal rain

Depressions Click on the red labels find out more!

Rain 1. Convective effects. 2. Thunderstorms. 3. Orographic (relief) rainfall. 4. Combination of wind and temperature. 5. Hyperthermia. 6. Hypothermia.

Sun 1. Intensity. 2. Direction. 3. Longevity. 4. Protection – Heat Stroke & De-hydration

Cold 1. Freezing level. 2. Lapse Rate = 1deg C per 100m height dry 3. Lapse Rate = 1deg C per 200m height wet 4. Frostbite. 5. Wind chill

Wind chill chart Celsius / Kph

Visibility 1. Cloud. 2. Snow. 3. Night. Navigating strategies.

Snow 1. Physical effect on movement. 2. Equipment. 3. Forecasts. TV, Radio, Web, Newspaper, Notice boards

Pressure Chart 12 Sep 2012

Snow Avalanche degree slope! 2. Wind slab formation. 3. Loose snow powder and wet. 4. Cornice / Serac failure.

Cornice failure risk

Altitude High >1500m 20% Oxygen Very High1500m > 5500m 10% Oxygen Extremely High5500m +5% Oxygen Death zone8000mNot enough!

The Physical Effects 1. Unpleasant. 2. Inconvenient. 3. Limiting. 4. Threatening. 5. Dangerous.

The Mental Effects 1. Demoralising. 2. Stress. 3. Decision Making? 4. Fear. 5. Panic. Grumble, mumble, fumble, stumble, tumble

As a last resort, Look out of the window!