Are you breathing out a cloud?

By Juman Hijab

Updated on: December 10, 2021 Original date: July 25, 2021

giant pumping out a cloud

Giant pumping out a cloud

What do breath and clouds have in common?

Breathing out into cold air will create visible breath.

A giant standing on Earth and pumping air from the ground to Troposphere could reproduce the fluffy cumulus clouds of a warm summer's day. This same giant's breath directed skywards could also produce clouds.

Why is that? Is breath really a microscopic cloud? Cold misted breath certainly looks cloud-like.

However, there are some differences between misted breath and clouds.   

Fluffy cumulus clouds

Fluffy cumulus clouds

Why can we see cooled down breath as clouds?

When the sun warms up the water in our oceans and lakes, a small number of water molecules change from liquid to gas. These gas-state water molecules are water vapor. Each gaseous water vapor molecule is lighter than the nitrogen and oxygen molecules in air. They rise up towards the upper Troposphere.

The gaseous state water vapor molecules remain separated until they cool down. It is then that a connected netting of cooled down water vapor molecules forms. This is the first step to forming cold breath and clouds.


Breathing out clouds of Invisible versus visible water vapor

In a cold environment, water vapor moves from an invisible state (warmer) to a visible one (colder).

  • Invisible Warm water vapor ---COOLING ----> Visible
  • Visible Cool water vapor --WARMING----> Invisible

A floating ghostly mass

The thing is that when water molecules cool down they form hydrogen bonds. Those are the bonds that allow one hydrogen atom to connect two larger atoms together (in this case two oxygen atoms).

hydrogen bonds

Cooled down and interconnected water vapor molecules create a web that ensnares air bubbles.

Air bubbles create scatter which reflects white light.  The net effect is that the enmeshed air molecules within a web of cooled down water vapor molecules show up as floating ghostly mass.


What about water droplets within clouds?

If clouds are a web of strongly attracted hydrogen bonded water vapor molecules, what about all the droplets of water that we know also exist within clouds?

Clouds form through a multitude of compounding factors:

  • cooling water vapor is only one of those factors
  • pressure effects of two high and low-pressure fronts bumping or crashing into each other
  • Changing temperatures and winds
  • Changing day/night temperatures
  • Ongoing addition of warmer water vapor that is rising from the earth's water surfaces
  • Multiple particles (dust, salts, other ions) within the mass of clouds allow for water vapor condensation

All those factors play a role in condensing a bunch of water vapor molecules. These coalesce into minute droplets. 


Icy breath

Icy breath

Breath and clouds

Clouds are masses and masses of cooled down water vapor nets encircling droplets of liquid water as well as air. Visible clouds are massive entities.  

One average sized cloud 1-kilometer long x 1-kilometer high will contain 500 million grams of water (or 500,000 liters). That's a lot of water.

To have a visual representation of that much water: A football field lined with 2-liter bottles side to side across the whole 360 x 160 feet breadth would give the equivalent of 500,000 bottles or 1 million liters of liquid.

Contrast that with one breath that contains 0.014 cc (= grams) of water (on the average, we exhale 400cc of water in 24 hours, almost half a liter). This is about 1 tablespoon each hour.

In other words, the slightly more than 1000 breaths that we breathe each hour will fill up that one tablespoon of water!

Are we breathing out a cloud? Yes, as both clouds and our breath are part of the same initial process: Cooling down water vapor molecules. Clouds are just a little more involved. 


Related courses

  1. White color in nature
  2. When is water white

Picture credits:

  1. Header image. By nik7ch,  Early in the morning, two morals left on glade, ID: 30565345. 
  2. Grafixo. Giant pumping out cloud, Aug, 2021.
  3. Nicholas A. Tonelli. Fluffy Midday cumulus clouds near Carroll, Clinton County, July 31, 2010.
  4. Thomas Brueckner “Hydrogen bonds” , Oct 7, 2005.
  5. webhamster. Icy Breath...-30º February evening, Feb 20, 2008. 

Juman Hijab

About the author

Juman is a retired physician after having been in clinical practice for more than four decades. Her lifelong interest has been in the chemistry of life.

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