Rare Fog Settles Over the Grand Canyon

Fog is a pretty common occurrence in most of the country, especially in places like San Francisco and Seattle. 

But this past Friday, the Grand Canyon awoke wrapped in a cloak of clouds.

Normally famous for its diving depths and colorfully stratified walls of rock and dirt, the rare fog even had veteran park rangers soaking in the majesty of the moment.

“Rangers wait for years to see it. Word spread like wildfire and most ran to the rim to photograph it. What a fantastic treat for all,” gushed ranger Erin Whittaker in a post on the Grand Canyon National Facebook page.

Flipping through the pictures, they are stunning, breathtaking and awe inspiring. But what caused this exceptional moment of wonderment?

Let’s talk about types of fog.  Despite that fact that all fog looks the same, there are actually six types of fog: Radiation, advection, upslope, ice, freezing and evaporation.

The fog at the Grand Canyon appears to be radiation fog, which is caused by the ground releasing much of its heat back toward space. As this release occurs, the temperature at the surface cools dramatically, creating what meteorologists call a “temperature inversion,” meaning the air higher up is warmer than what’s at the ground.

As the air continues to cool, the ambient temperature creeps closer to the dew point—a measure of moisture in the atmosphere. When the air temperature and dew point are at the same value, saturation occurs. Basically, the air is at 100 percent relative humidity.

At saturation, water vapor can condense, changing from a gas to a liquid. The little drops that develop start to form a cloud close to the ground and fog is born.

In addition to fog on Friday morning, another round formed on Sunday. And this time the air temperature was well below freezing, causing freezing fog. The water droplets that form are “supercooled” — meaning they are still liquid, but below freezing. These supercooled droplets then instantaneously freeze to any object that’s at or below 32 degrees.

Aside from the cool science behind the formation of the fog, these pictures remind us of the intrinsic beauty of nature. Take some time to go through the photos and enjoy their splendor. They’re truly stunning.
http://www.weather.com/news/science/rare-sight-grand-canyon-20131202