The Earth is the vehicle. The Sun is the engine.
Many books have been written about the nature and patterns of weather. My excellent reference book is 'Mountain Weather' authored by Jeff Renner and published by The Mountaineers Books. The Weather Network can provide helpful information but mountain weather is often regional and dynamic. Mountain Weather is an excellent website and, with a bit of practice, provides excellent intelligence.
In coastal mountain ranges, weather patterns can be complex and spontaneous.
The weather can be an awesome and important part of any wilderness experience.
The intent in this article is to share some of what has been observed and learned over many years in a non-technical, informative way. Occasionally, powerful events are a demonstration of Mother Nature's great, spellbinding beauty and abundant sense of humor.
As the sun warms the perpetually rotating Earth, water, air and terrain are warmed and weather patterns are created. Water evaporates, rises and accumulates to form clouds. The high altitude jet stream nudges weather patterns across the surface of the Earth. Areas of higher pressure cause air to rise: low pressure zones cause air to descend. High pressure zones obviously move to occupy low pressure zones so air is moving in a circular pattern vertically as well as horizontally. The invisible area between a high and low pressure zone is a moving front.
It is important to understand this constant flow can increase dramatically in pace and intensity as altitude increases. The majority of hiking days are chosen for fair weather. Scanning the sky en route to the trail-head may help estimate the nature and direction of weather systems. Predictions, sometimes successful and often not, can help the days preparation for the impact a rising sun will have on current conditions.
The precise angle of a moving front will channel air through the mountains in the path of least resistance. A minor change in the angle of any front can change the path of the weather very rapidly. It never ceases to amaze how mountain weather can change so abruptly. The uncertainty is the reason extra layers and gear for wind and rain are always carried in the backpack.
Here is how a typical, well-chosen day may shape up in the mountains. An early start is in cool, still air. The sky is clear and low-angled light enhances color and contrast. When gaining elevation the temperature commonly declines which is helpful to counter the generation of body heat. Commonly, tiny, sporadic white clouds begin to form as the sun warms up the air and ground.
Breaking the tree line onto open ground, breathtaking views progressively expand. If ascending Mount Rundle in Banff National Park, a glance at the prominent, pyramidal peak of 11,871 ft. (3,618 m) Mount Assiniboine to the south can often assist in determining upper level wind direction and change in cloud height. Normally, cloud will build and darken as the day progresses. Breeze is often more prominent in mid-afternoon. When cloud descends on a tall, pointy peak like Assiniboine, the rate of descent of the ceilings can help assess the potential for storms.
Often cloud will drift and dance up and down a distant peak in magical slow motion as the sun battles the cloud cover. I am paying close attention to the direction cloud formations are moving. Breeze against skin alerts of changes in wind velocity and direction. If the winds increase abruptly, it is often accompanied by a noticeable drop in temperature which indicates the presence of a front and a potentially significant change in weather conditions. If heavy, dark cloud formations change direction and begin to approach, abandoning the mission and making a hasty descent to safer ground may be the most sensible alternative.
The weather provides instructions on how to proceed. Is that cool or what? It is like having an ongoing and meaningful conversation with nature.
Often, at high altitude, there is awesome, active weather. The combination of wind, evaporation, sun, cloud and the friction of opposing air streams create amazing variations of powerful, full surround sound weather with the cool, fresh air in the face. You can't buy this stuff.
A picture does the spectacle no justice. A Smartphone cannot provide this experience. You need to get out there. The marvel is mesmerizing and saturated with mixed feelings and emotions. Sometimes you want to stay but experience tells you to leave.
Lightning deserves a great deal of respect. At high elevations hikers are a potential target. If you allow a lightning storm to sneak up on you and you happen to be near or on the summit of a mountain, it is not a good time to raise your hiking poles in the traditional sign of victory. If a buzzing is sensed, there may be imminent danger.
The advent of satellite weather images has been extremely helpful. The 'big picture' shows cloud formation and movement. Spacing between isobars (lines of equal atmospheric pressure) indicate potential intensity. Whenever possible, check satellite images on the weather network.
There are two important weather relationships worthy of review. They are:
- Wind chill, (the combination of cold temperature and wind velocity), and
- Heat stress (the combination of hot temperature and humidity)
Increased wind speed combined with low temperatures can exponentially increase the risk of frostbite on exposed skin. High temperatures in high humidity are also dangerous. In these more extreme conditions, action is required to maintain a reasonable range of core body temperature. It is wise to avoid or extricate oneself from these situations.
A book could be written about altercations with weather that range from fabulous through exciting, boring, character building, powerful, spectacular, awe-inspiring to downright comical. Enjoy the pictures.
Sun behind smoke over Canmore from a forest fire in Kananaskis Country