Lenticular clouds and special mountain waves

The Northwest is a place of great physical beauty and that charm extends to the sky.

Perhaps there is no better example than the lenticular clouds and mountain waves commonly seen here. The display of the past few days has been phenomenal.

In recent days, I’ve seen some beautiful prism clouds (lenticular clouds) over Puget Sound, but the most dramatic has occurred west of the peaks of the Cascades.

Let me show you a few photos produced by Mount Adams, courtesy of the best glass-shaped photographer in the area: Darlisa Black. And I’m also going to give you a little bit about wave mountain 101.

This is a photo taken by Darlisa on Friday (looking north, west is left).

Look closely and you’ll see a lenticular formation just above Mount Adams, roughly symmetrical to the top. That is often called hat cloudand it is the result of air being pushed up by the mountain until it reaches saturation (100% relative humidity).

Darlisa Black’s photo

But even more impressive are the stacked lenticular clouds downstream (west) of Mount Adams). These clouds extend to high altitudes in the atmosphere and are associated with mountain waves propagate vertically. Pandemic: vertical spread This means that waves can extend over large vertical distances.

This is a close-up view of vertically traveling wave clouds. Rub.

They look like plates stacked on top of each other. This may be due to changes in the humidity in the atmosphere. I also suspect that there is some sort of mechanism of instability contributing.

Mountain clouds 101

In fact, there are three types of lenticular clouds seen around here.

The first is a pyramidal cloud right over the top of the mountain, as said in the first photo. A schematic is shown below. Clouds form on the upwind side of the terrain and dissipate downstream as the air sinks.

Then there are waves that can be generated downstream of the peak that remain or are trapped in the lower atmosphere (see below). Known as wave lee stuck, this situation can produce spikes far from the terrain ….. even sometimes over the Puget Sound or the Columbia River Basin east of Washington.

Sometimes these trapped lee waves are so obvious on high-resolution visible satellite imagery as cloud lines parallel to mountain peaks. Exactly this situation occurred yesterday downstream of the Central Cascades (see satellite image below, arrows show characteristics).

The final configuration is shown below: mountain waves propagate vertically. When currents approach terrain with the right characteristics, mountain barriers can create mountain waves that travel upward and amplify, creating clouds (usually lenticular or lenticular) in the troposphere above (about 15 to 30 thousand feet above the surface). This is the process that creates the beautiful clouds downstream of Mount Adams shown above.

These vertically spreading clouds are also quite evident in the satellite image, as shown in the Friday afternoon image shown below. The red arrow indicates Mount Adams. The white orbs to the west are vertically-propagating mountain-wave clouds.

The wave clouds in the mountains can be stunning at sunset (see image taken by UW Physics Professor David Kaplan from Cle Elum). Some provide useful supplies to glider pilots, providing welcome lift, but they can also create strong turbulence, especially high amplitude versions of the vertically propagating variety.

David Kaplan’s photo