Clouds and the Water Cycle

A cloudy morning at Bandelier National Monument. (Photo by Sally King/NPS)

By Jean Dewart

Let’s go back, to a time “before clouds.” The air is primarily made up of gases — oxygen and nitrogen — that are invisible to our eyes. Oxygen is about 78% of the air and nitrogen is about 21% of the air. That accounts for 99% of the air! So, the rest of the atmosphere is made up of trace gases that can change depending on time and place.   

One of these trace gases is water vapor — that is, water in its gaseous form. It turns out that Earth is the “goldilocks” planet (that is, it’s just right!) because at the temperatures found on the earth’s surface and in the atmosphere, water can exist in each of its three phases: gas (water vapor), liquid (water), and solid (ice).

Our atmosphere has water vapor in it all of the time — sometimes only a little and sometimes quite a lot. Relative humidity is one way to describe the amount of water vapor in the air. If there were no water vapor in the air (this rarely, rarely happens, and only in very, very cold weather), we describe this as 0% relative humidity. If the air had as much water as it could hold, we describe this as 100% relative humidity. The air in Northern New Mexico is usually between 30% and 60% relative humidity near the surface of the earth.

How does water vapor get into the air? Primarily from evaporation of liquid water from the oceans, rivers, and lakes of the world. In Los Alamos, where we’re far from major bodies of water, water vapor is brought by the winds coming from the Pacific Ocean, the Gulf of Mexico, or the Sea of Cortez (Gulf of California).  

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Image Credit: NASA

For a cloud to form, the air must have 100% relative humidity. This allows the water vapor (gas) in the air to condense into liquid water. To get air to 100% relative humidity, the air must usually be cooled. Air can be cooled by lifting it above the ground — sometimes to as high as 20,000 ft above the ground! Air at the earth’s surface can be lifted by winds hitting a mountain (topographic lifting), by a cold front, or by the sun warming the ground and heating the air next to the ground. 

In each case, air will rise (and cool) to a height where the relative humidity is 100% and cloud drops begin to form. If air is lifted high enough, the air can cool enough to form ice crystals instead of water droplets.

Here are the different types of lifting of air in the atmosphere.  

Example of topographic lifting of air to produce clouds:

http://ww2010.atmos.uiuc.edu/guides/mtr/cld/dvlp/gifs/org1.gif
Image Credit:  University Corporation for Atmospheric Research

Example of a cold front lifting air to produce clouds

Cold Front
 Image Credit:  University Corporation for Atmospheric Research

Example of surface heating of air to produce clouds:

Diagram of how surface heat creates clouds
Image Credit:  University Corporation for Atmospheric Research

What clouds did you see today?

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Were they a large gray, flat cloud, with primarily uniform features? These are stratus clouds. (Photo by Jean Dewart)
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Did you see large fluffy and puffy clouds? These are cumulus clouds. (Photo by Jean Dewart)
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Were they thin wispy clouds high up in the sky? These are clouds made of ice, and they are called cirrus clouds. (Photo by Jean Dewart)

If there is rain, then it is a cumulonimbus or nimbostratus cloud. Which one is this?

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(Photo by Jean Dewart)

Although you cannot see the top of the cloud in this photo, the rain being organized into a shaft indicates that this is probably a cumulonimbus cloud. Nimbostratus clouds usually have widespread rains, coming down from many parts of the stratus cloud, rather than in distinct shafts as in this photo.  

The World Meteorological Organization has developed a classification of cloud types. To see this, and learn a lot more about clouds, visit their webpage.

Week 2, Day 5: Spring Weather & Clouds

Storm clouds over the mesas of Los Alamos. (Photo by Craig Martin)

Explore New Mexico’s spring weather and clouds in today’s Take It Outside post. We will have a Saturday bonus post up tomorrow morning exploring spring astronomy and celebrating Earth Hour

Then, join us on Monday, March 30 to learn more about our four-legged friends in Northern New Mexico! We’ll look at scat, tracks, native reptiles and amphibians, black bears, mountain lions, and more.

Upcoming Event:

Join Galen Gisler this evening for a virtual astronomy talk! Galen will discuss the age of the Earth and how we know it. This talk is free to watch, but registration is required. Learn more and sign up here.

Blog Post:

On the blog today, atmospheric scientist and McCurdy Charter School sixth grade teacher Christy Wall shares some facts about why spring weather in New Mexico is so unpredictable. Check out her post here.

Time lapse of moving clouds taken at Piñon School. (Video by Beth Cortright)

Craft:

Make a cloud in a jar! Follow these simple instructions from NASA to make a cloud in a bottle using some basic kitchen tools, warm water, ice, and a match. Adults should help children with this project.

What does your cloud look like? Tell us about it or share your photos!

Outdoor Challenge (Beginner):

Head outside and observe the clouds in the sky! Take your nature journal with you and use cotton balls or colored pencils to make pictures of the clouds you notice. Can you identify what kinds of clouds you’re seeing? Use this chart to help you!

Wait a few hours and head outside again. What do the clouds look like now? Have they changed? Tell us what changes you notice!

Outdoor Challenge (Advanced):

Observe the clouds today and classify them by:

  • Cloud type: Identify the type of clouds you see using this dichotomous key.
  • Cloud cover: How much of the sky is covered by clouds? Use the graphics on this page to help you estimate.

Share your classification with us! It will be interesting to see how everybody’s observations compare throughout the day.

Other Resources:

Share Your Experience:

Tell us what signs of spring you notice this week! We’d love to see your photos, too. Please send them to takeitoutside@peecnature.org or share them on Facebook or Instagram with the hashtag #peectakeitoutside.

Join us tomorrow morning for a special weekend bonus post! We’ll explore spring astronomy so you can stargaze over the weekend and celebrate Earth Hour.

New Mexico Spring Weather

A cloudy spring sky seen from Abiquiú, New Mexico. (Photo by Christy Wall)

By Christy Wall, Atmospheric Scientist and 6th Grade Teacher at McCurdy Charter School

Have you ever heard somebody say “If you don’t like the weather, wait around a few minutes. It will change.” This statement is usually true for weather in the spring, especially when you live in New Mexico!

You might be wondering: “Why is our spring weather so unpredictable?” In the spring, New Mexico begins to get more sunlight as Earth rotates on its tilted axis. More sunlight means warmer temperatures, and this sets the stage for a battle between cold and warm air. These differences in temperature cause differences in air pressure — and differences in air pressure result in wind!

Clouds near Los Alamos, NM. (Photo by Craig Martin)

During winter, a band of strong winds high in the atmosphere called the polar jet stream transports weather systems into New Mexico. You’ll often hear meteorologists talk about cold fronts, which are the boundary of an approaching area of cold air. During winter, cold fronts often bring snow storms and very cold temperatures. In the days before these fronts pass, we often have strong winds from the south.

As winter becomes spring, the polar jet stream begins to move north, but sometimes it still dips far enough south to bring a cold front to New Mexico. One big difference in spring is that the south winds before the front bring warmer air with them. These days often feel abnormally hot. When the cold front moves through, it can still bring snow and cold temperatures with it. This means that the days prior to the arrival of the front can feel like summer, but when the front passes, we’re back to winter. If the polar jet stream doesn’t dip quite far enough south, New Mexico may miss out on the snow, but still have slightly cooler temperatures and high clouds when a cold front passes through.

My favorite part of spring is the change in our clouds. In the winter, the clouds we see overhead are primarily made of ice. Once it gets warmer, we have clouds made of both ice and water. This sets the stage for my favorite weather phenomenon — thunderstorms! As the ground heats up in the spring, rising air produces a special kind of cloud called a convective cloud. These clouds grow through vertical motion, making really cool shapes.

You can contribute to cloud science by noticing the clouds and reporting what you see to the GLOBE (Global Learning and Observations to Benefit the Environment) Program. GLOBE is a worldwide science and education program sponsored by NASA that helps us all learn more about our Earth systems and changing climate.