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. I also lean heavily on The Weather Network. In coastal mountain ranges, weather patterns can be complex and spontaneously. I am not an expert in weather systems, by any stretch of the imagination, but I know what I have seen and experienced. It can be an awesome and important part of any wilderness experience. My intent, in this blog, is to share some of what I have learned over many years in a non-technical, informative way. Occasionally, powerful events are a demonstration of Mother Nature’s great, spellbinding beauty.
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 my days are chosen for fair weather. I will scan the sky en route to the trailhead and estimate the nature and direction of weather systems. I try to predict, sometimes successfully and often not, 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 miniscule change in the angle of any front can change the path of the weather very rapidly. It never ceases to amaze me how mountain weather can change so abruptly. It is the reason I always carry those extra layers and gear for wind and rain.
Here is how a typical, well-chosen day will shape up in the mountains. An early start is in cool, still air. The sky is clear and low-angled light enhances colour and contrast. As I gain elevation the temperature 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. When I break the tree line onto open ground, breathtaking views progressively expand. As an example, if I am climbing Mount Rundle in Banff National Park I will glance at the prominent, pyramidal peak of 11,871 ft. (3,618 m) Mount Assiniboine to the south. 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, I can judge the rate of descent of the ceilings as well as the potential for storm. 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. My skin alerts me to changes in wind velocity and direction. If the winds increase abruptly, it is often accompanied by a noticeable drop in temperature. I am in the presence of a front and a potentially significant change in weather conditions. If heavy, dark cloud formations change direction and begin to come towards me, I will abandon the mission and make a hasty descent to safer ground. The weather gives me instructions on how I should proceed. Is that cool or what? It is like having an ongoing conversation with nature.
Often, at high altitude, I witness 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 your face. You can’t buy this stuff. A picture does the spectacle no justice. A Smartphone cannot give you 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 lot of respect. At high elevations you 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 you sense a buzzing, you are in danger. I have had this happen twice. Both instances, which had nothing to do with summits, occurred many years ago. The first was in a sailboat on Lake Ontario when my friend and expert sailor compromised his better judgement to give my son his first experience in a sailboat. The air was humid, we were the highest point on the lake and the buzz and crackling in the mast was apparent. It was a short trip and dry land looked good. The second instance was during a hike on Mount Seymour near Vancouver, British Columbia. My son, Bill, and I were hiking in light rain under umbrellas when we came to a place where major power lines were overhead. I jumped up onto a huge log to have my picture taken. The electricity from the power lines was crackling in the steel frame of the umbrella. When you hear it, you will recognize it immediately. I must confess I have flirted with lightning closer than sensible. It is easy to be swayed by the powerful performance. It is always better to err on the side of caution.
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, I 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. I avoid or extricate myself from these situations.
I could write a book about my encounters with weather that range from fabulous through exciting, boring, character building, powerful, spectacular, awe-inspiring to downright comical. Enjoy the pictures.