Mountain Weather Unpredictable - Explains how it's difficult to predict weather in the mountains. - http://www.main.nc.us/graham/mcclung/Mountain%20Weather.html
Rocky Mountain National Park Weather - Explains the weather you're likely to see at different times of the year. - http://rockymountainnationalpark.com/weather/default.htm
Mountain Weather - Contains soundings for several locations which show how the temperature and dew point change with altitude. - http://inte099018.halls.colostate.edu/~vigh/weather/mountain_weather.htm
BBC: Weather at Altitude - Looks at how the weather is different at high altitudes. - http://www.bbc.co.uk/weather/features/understanding/altitude.shtml
NOVA: Volcano Above the Clouds - Find out how mountains create their own distinct weather patterns, often causing wet weather on one side and a dry, clear climate on the other. - http://www.pbs.org/wgbh/nova/kilimanjaro/weather.html
Met Office: Mountain Safety - Highlights several dangers about the mountains, whether going for a long expedition or short hike. - http://www.metoffice.com/loutdoor/mountainsafety/
USAToday.com: Understanding Mountain Weather - Talks about avalanches and winter weather see on the mountains of the United States. - http://www.usatoday.com/weather/wmountn0.htm
MountainWeather.com - Contains weather information for Jackson Hole, Wyoming, USA and the Teton Mountains. Radar images and forecasts. - http://www.mountainweather.com/