June 25, 2014

Clouds Tell You a Story

Can you tell what clouds are made of by looking at them?   To a considerable degree you can.  There are really just three possibilities:
  1. Clouds made of ice crystals
  2. Clouds made of water droplets
  3. Clouds made of BOTH ice crystal and water droplets.
And there is a major complication you might not be aware of:  clouds can be made of water droplets even when temperatures are below freezing (0 C, 32 F).  This is called supercooled water.  Turns out water droplets don't have to freeze until temperatures get way cold, -40C (-40F), although the amount of supercooled water tends to drop off rapidly as temperatures fall below roughly -15C.

Interpretation rule 1:  Clouds with sharp edges and predominantly made of water droplets.
 Take a look at this picture of a growing and massive cumulus cloud.  Edges are sharp, so mainly liquid water.

Interpretation rule 2:  Clouds with soft, fibrous, and diffuse edges are generally made of ice crystals.

Like this example of a cirrus cloud.

You don't need the cone to know the clouds are made of ice crystals in this picture.  Wispy and diffuse edges.

You can also tell a lot about whether the atmosphere is turbulent or unstable by looking at clouds.

When the atmosphere is relatively stable and laminar (not a lot of vertical mixing), the clouds are layered.  Like this:

By when it is bubbling up with turrets (like this cumulus), the atmosphere is roiled by thermals and mixing.

Or if the clouds look like waves breaking on a beach, looking out for a lot of mixing and turbulence:

And there some clouds you are better off not knowing about:

We deal with such clouds in graduate school.


  1. Great post Cliff. I loved this one and your other post about how to tell if rain is falling out of cloud. Me and my daughter have a good time guessing that on our hikes

  2. Cliff: After learning about nautical twilight we can handle those hook shaped clouds. Hit us!

  3. The ice cream cone was awesome! Do you guys have any thoughts on weather the Sierra Nevada mountains will see more snow this winter? We just moved here from the Sacramento area and it was my first year living in the snow. Boy what a disappointment! I was looking for more snow than what we got!

    Bounce House Rentals Sacramento


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