Playing in perfect powder snow on a calm, clear, cold day is as good as it gets here in Wyoming’s Teton Range.

Some skiers, snowboarders, and snowmobilers have it good more often than others: local backcountry travelers who really know where to go can find soft snow somewhere almost every day of a typical winter.

Shhhh!  It’s a secret.

High pressure between storms typically brings Wydaho bright blue skies, light winds, and cold temps: conditions perfect for the preservation of powder.  Remote ridges shelter sinlessly sweet sugar, proud peaks protect perfect pow-wow-pow weeks after the last scrap of soft has been scavenged by lift-serviced skiers.

The climate and geography of this area are truly a wonder of Nature, as they are in the mountains in general.

Let us regard snow quality from a skier’s perspective.

Surroundings, slope aspect, elevation, vegetation, solar shading, and wind are obvious factors, but excessive infrared bouncing around turns soft snow to toast.  Too much heat can ruin fresh snow and cause dangerous conditions on all aspects.

We’re not just talking about air temps though.  Let’s remember that electromagnetic, aka radiant, aka infrared heat travels at the speed of light and snow sucks it up and adjusts accordingly before belching it back out again nanoseconds later.

Utah Avalanche Center Director Bruce Tremper explained this phenomenon clearly in his masterpiece, Staying Alive in Avalanche Terrain:

Radiation usually controls snow surface temperature much more than air temperature — something that takes most people by surprise.  If you want to understand snow and avalanches, you need to get this concept firmly down, so let’s take a moment to dive in under the hood and get our hands dirty…

The energy that reaches the Earth from the sun is composed of different wavelengths.  First, there’s visible light and ultraviolet radiation, which scientists call short-wave radiation, and second, there is heat, which we call long-wave radiation.

Even though the snow is white — meaning that it reflects most visible light — when it comes to the heat part of the spectrum (long-wave radiation) snow is a nearly perfect “black body radiator” as physicists describe it.  This means that it absorbs almost all of the radiant heat that reaches it and likewise, it very efficiently reradiates any heat it contains.  In other words, if you shine a flashlight on snow, it reflects most of the energy, yet if you shine a heat lamp on the snow, it absorbs the energy and warms up quickly…

It’s obvious enough that clouds can prevent much of the radiation from the sun from reaching the snow surface, but much less obvious how clouds block and trap radiation from going in the other direction — from the snow surface to the sky.  When the snow radiates its heat toward the sky, clouds can capture that same radiation and reradiate it back to the ground again, which we call the greenhouse effect.  In other words, we can think of clouds like giant heat lamps in the sky.  The snow surface can become much colder without clouds overhead than with clouds….

During the day, the greenhouse effect warms the snow surface most dramatically when the clouds are thin enough to allow some solar radiation to get though but thick enough to capture some of the outgoing radiation as well.  This commonly happens with thin, wispy clouds, such as cirrus, or with a thin layer of fog or low clouds.  For instance, you may be enjoying great, cold powder on a clear day and then when fog or thin high clouds appear, suddenly the powder turns into something resembling mashed potatoes.  Usually the air temperature didn’t change very much, just the radiation balance.*

Unfortunately, mashed potatoes and windhammered hardpack are becoming more common in the Tetons.  In recent years we’ve see more wacky weather, more extreme temperature fluctuations, and more wonky snow.

All too often the storms come in too warm for pow, or it gets too warm immediately following a storm.  Last week’s 80*F temperature swing from -40*F to +40*F and subsequent winds totally trashed what was good and could have remained good.  Mountain Weather meteorologist Jim Woodmency made graphs documenting this extreme weather oddity.

Atypical weather is often blamed on anthropogenic climate change, and CO2 takes the rap in the mainstream media version of reality.  In actual reality humans are changing the climate in many ways, and CO2 is only a minor player among bigger anthropogenic factors.

People paying attention have noticed a change in the sky and to the snow.  Even during prolonged periods of high pressure, bluebird days are not the norm.  More often we see the thin wispy cirrus clouds that turn powder into mashed potatoes.

Strangely, these cirrus clouds appear to be induced by airplanes.  Some planes leave trails that linger.  Some don’t.  The trails that linger grow into cirrus clouds covering up what had been a bright blue sky.  These cirrus clouds trap enough heat to drastically transform our snow conditions.

A 2011 German study published in Nature Climate Change found that aviation contrails –which are essentially artificial clouds — contribute more to human-propelled climate change than all the CO2 pollution created in the history of fuel-powered aviation.

There are ~12,000 commercial aircraft continuously flying 24/7/365 globally.  Most of this air traffic is over the United States and Europe.  Nationally, regionally, and locally planes are inducing cirrus clouds over places like Jackson Hole almost every day.  I’ve been watching it happen closely since 2012.

People all over the world are documenting this, and many of us are very concerned about it.  It’s not normal.  It’s not natural.  It affects us all.  It’s not OK.

I gathered some field evidence of this phenomenon yesterday while skiing.  Here it is.

Real world observation is the foundation of science.  Modelling is modelling.  Climate models forecasting the distant future don’t include the impact of aviation, weather modification, or weather warfare.  Humans have been attempting to manipulate the weather for centuries, and have been doing it successfully using airplanes emitting chemicals since the 1940s.

It’s not rocket science: it’s chemistry, meteorology,   thermodynamics, and fluid dynamics on an astounding level made possible by supercomputing technologies.  It’s real climatology, not the fake kind we read about in the papers.

I think the avalanche experts have an ethical question to consider because the hard science is settled: can airplanes cause awful conditons?  Yes. Do cirrus clouds induced by aircraft affect mountain temperatures, snow quality, and snow safety?  Can they cause avalanches?  Yes.

This prompts an obvious ethical question: how do we stop them?  Not the avalanches, but the planes.

Here’s what high pressure is supposed to look like over the Tetons:

Here’s what jet trash looks like when it’s screwing up our weather and snow:

One Love.  Peace.