Cumulo-a-Palooza!

Guess how high these low clouds are? 

  The lowliness of cumulus clouds is easier to recognize if there are mid-level clouds in the same sky. Take yesterday. The sky was full of smallish cumulus clouds--the puffy ones with gray shading in the photographs I have posted here--and, above them, patches of clouds that were clearly floating above them.

  The cumulus clouds rest at altitudes ranging from ground level to about 6,500 feet. I cannot estimate the height of other clouds. "Low" works fine for me.

  The higher clouds are a type of mid-level cloud known as altocumulus. (Yes, "alto" means "high," but meteorologically it means "mid"). Altocumulus clouds are found at altitudes ranging from 6,500 to 18,000 feet. "Mid-level" works for me. I will explain why at the end of this posting.

  I have zoomed in on the clouds here--take a look so you can get a better look at the two levels--the large gray and white cumulus below and the smaller, fleecy altocumulus above.

Cumulus below, revealing patch of altocumulus above.

Here they are again, even closer so you don't have to find your reading glasses.

 A heart-shaped cumulus cloud! It must have noticed me staring.

   It always takes my eyes and brain a while to see the depth of the sky, to see that what I might initially describe as "behind" is actually "above," to see the sky not as a celestial dome but a celestial sandwich. From our perspective on earth, the land we stand on is flat and the sky is flat. We cannot observe the curve of the earth nor the curve of the atmosphere that surrounds it. We do not live in a snow globe.

  Take a look at the photo below. These are cumulus clouds--cumulus humilis because they are wider than they are tall. The bases of all of these clouds--from the top right of the photo all the way back to the horizon point in the lower center of the photo--are resting at the same altitude. All of these clouds are the same height.

Flat flat flat.

    Look again after reading this: as your eye moves from upper right to lower center, do not let the clouds sink down toward the earth. Keep their bases up there at the same level. Do not let the clouds and the earth touch at the horizon. You're getting it if you feel your eyes and brain arguing.

   Now, for the reason I have not yet mastered estimating cloud heights. I don't own a gizmo such as a lidar detector or a ceilometer (below).

This ceilometer is used by the Atmospheric Radiation Measurement Program of the U.S. Department of Energy. 

Photo source: http://www.arm.gov/instruments/vceil

 And because knowing the height of cumulus clouds involves a formula that requires subtracting the dew-point temperature from the surface temperature and then multiplying by 125. You can remember this formula as as H = (T-DP) x 125. If you have a smart phone in the field, you can get the current temp and dew point from the NOAA website and probably do the math in your head.

  If you're not so equipped, you can find the numbers later on your computer. Like I just have.

  Yesterday at 12:51 p.m., when I took these photos, the temperature was 46 degrees F and the dew point 35 degrees F. (Recall that dew point is the temperature below which water vapor condenses). So, that's an 11 degree difference, multiplied by 125 equals 1,375.

  Voila. The cumulus clouds in the photos above were floating 1,375 feet above the earth.

   I will try to understand why this works and explain it all to you in an upcoming post.

Look at the clouds! Do the math! Amaze your friends!  

Click here for NOAA website. Enter the zip code in the upper left for current conditions (including surface temp and dew point) in your area or wherever your cumulus clouds were hanging out. If your cloud photos are a few days old, use the link to "3 Day History" for the hourly temperature, dew point, and other data.

How High Are the Low Clouds?

Strange as it seems, all these clouds are the same height, that is, their bases all rest at the same altitude. These are cumulus clouds, one of the "low" clouds.

  For me, one of the most challenging aspects of studying the clouds is determining how high they are above the earth. Most meteorology books and cloud charts provide altitude levels for the ten basic cloud types. (Recall that altitude is the height of something above the earth, elevation is the height of something attached the earth--such as a mountain or office building).
   Cloud heights are given in feet or meters and describe the altitude of the base of the cloud, the base being synonymous with the bottom of the cloud. Let's look at a few examples of low clouds--clouds with their bases resting from ground level up to 6,500 feet (2000 meters). Low clouds include stratus, stratocumulus, cumulus, and cumulonimbus. I find this strange because this means low clouds include the ground-hugging fog (a type of stratus) as well as the towering cumulonimbus clouds, which often rise to the top of the troposphere at 39,000 feet (12,000 meters).
 

Here we have very low stratus clouds (the fog) skirting this foothill in the Cascade Mountains and  low stratocumulus clouds above them.

The gray cloud is a type of cumulus cloud called cumulus fractus--a  remnant of  a larger cloud. These often form below other clouds, including the cumulonimbus in the background here. I couldn't capture the entire cumolonimbus here, but the telltale dark base and wispy-edged anvil-shaped wedge in the lower right corner of the photo are the give-away. That, and the fact that there were other cumulonimbus clouds in the area that day. And I got soaked by one of them.

Here (from my last posting) is a "low" cumulonimbus rising behind and from  its dark and stormy base where other low clouds--cumulus and stratocumulus cavort. (Photo courtesy M.D. Ruth)

T. Rex of the Sky

Cumulonimbus clouds rising over Puget Sound.   Photo courtesy M. D. Ruth

      It was hard to miss these towering clouds if you were out and about anywhere in Puget Sound today. These are culumonimbus clouds--the tallest of the clouds--showing its flattened anvil shape at its icy top. Because of the anvil shape, these clouds are more precisely described as cumulonimbus incus. If you watched long enough you might have seen the tops spread out in wisps, or hairs--turning them into cumulonimbus incus capillatus--and you into a Latin scholar! Incus means anvil; capillatus means hai-like.
  These clouds are composed of water droplets in their lower portions and ice crystals in their upper portions. This was a cumulus congestus cloud (the big, cauliflower shaped ones) earlier in the day and rose through the troposphere under its own power --power produced within it as water molecules in the cloud condensed into droplets and released a tiny amount of heat (called latent heat). The cumulus congestus  continues to build until it reaches the troposphere/stratosphere boundary, called the tropopause, beyond which the air temperature begins to increase with altitude. When the cumulus congestus cloud hits this boundary, it can no longer rise, so it flattens out and assumes its distinctive anvil shape and its status as a cumulonimbus.
   Though cumulonimbus clouds are considered "low" clouds because their bases are low--just 2000 feet above the earth's surface. These majestic clouds are the tallest of the clouds, rising up to 40,000 feet above the earth.
   As you may remember, "nimbus" implies rain. And though Olympia was dry while this cloud was putting on its show this afternoon--some places to the northwest were getting hammered. With rain, maybe hail. Maybe drinks, too--but that's mixology, not meteorology.
  Cheers to the Clouds!

Rare Bird Flies Again

  It is with barely contained excitement that I share with you this good news: The Mountaineers Books is reissuing my book, Rare Bird: Pursuing the Mystery of the Marbled Murrelet in paperback in September 2013.

   It's been eight years since the hardback edition was first published and I am thrilled to be introducing my favorite bird to new audiences and that The Mountaineers Books is putting their imprint on the book with a new epilogue, an index, a section on helping the murrelet, and an arresting new cover (sneak preview in an upcoming post).

  Rare Bird has found the perfect new home.  For those of you new to The Mountaineers Books, they are a Seattle-based publisher with 500+ titles in print, focusing on recreation, lifestyle, and conservation. They are the publishers of natural history books. including ones on birds of arctic, caribou, beluga whales, polar bears, and urban goats. No doubt you own one or several of their popular "100 Classic Hikes" or "Best Hikes" series of guides or the bible of mountain climbing, Mountaineering: Freedom of the Hills (8th edition).

   I so wish I had read this bible before I began following biologists into murrelet habitat. I would have gotten in shape. I would have understood contours maps and, therefore, the difference between a "stroll" and an "uphill battle." I would have brought my own stick to scare off the mountain lions. I would not have worn cotton, the death fabric. But memories (and stories for Rare Bird) were made from near-death experiences in the wilderness.

   Which is not to say you have to go off trail and bushwhack your way through an old-growth forest to experience the world of the marbled murrelet. Let the professionals do that. Let your armchair transport you into the Pacific Coast's old-growth forests. You know. The arm chair next to the reading lamp. The armchair with the little table next to it, the table waiting to hold the Mountaineers Books'Rare Bird.

Artwork by Paul Harris Jones will again  grace the pages of Rare Bird