Is there something in your life that gives you the sense that everything will be okay, that everything will work out? Clouds give me this sense of security. Clouds have the unique ability to change shape — allowing what we see to be informed by our imagination.
The science of clouds is fascinating. Did you know a cloud is made up of a large collection of very tiny droplets of water or ice crystals? These droplets are so small and light that they float in the air. All air contains water, but nearer to the ground it is usually in the form of an invisible gas called “water vapor.”
When warm air rises, it expands and cools. Cool air cannot hold as much water vapor as warm air, so some of the vapor condenses around tiny pieces of dust floating in the air, forming a tiny droplet around each dust particle. When billions of these droplets come together, they become a visible cloud.
Clouds can form anywhere in the troposphere, and although they are made up of condensed liquid, they are light enough to float in the air and be moved from place to place by the wind. The characteristics of clouds are dictated by the elements available — including the amount of water vapor, the temperatures at that height, the wind and the interplay of other air masses.
Clouds are classified according to appearance and height. Based on appearance, there are two major types of clouds:
- Clouds of vertical development, formed by the condensation of rising air.
- Clouds that are layered, formed by condensation of air without vertical movement.
When clouds are classified by height, there are four classes: high, middle, low and vertical development.
| Classification | Cloud Name | Average Composition | Height of Bases |
|---|---|---|---|
| High | Cirrus Cirrocumulus Cirrostratus | Frozen water droplets or ice crystals | 20,000 feet |
| Middle | Altostratus Altocumulus | Ice crystals and/or water droplets | 6,500 — 20,000 feet |
| Low | Nimbostratus Stratus Stratocumulus Fractostratus | Water droplets (ice crystals in winter) | 50 — 6,500 feet |
| Vertical | Cumulus Cumulonimbus | Water droplets at lower levels and ice crystals at upper levels | In low cloud range |
Cloud names, of which there are twelve, combine the characteristics of appearance and height. A brief description of the root name will indicate this combination of features.
Stratus, strato...Layered or sheetlike
Cumulus, cumulo...Puffy, heaped (vertical)
Nimbus, nimbo...Dark and rainy
Cirrus, cirro...Curly, featherlike (high cloud)
Alto...High (but used to describe a middle cloud)
Fracto...Broken
Knowing about clouds and how they are formed makes the magic of cloud watching an educational adventure. All you have to do is look up, and perhaps you too will find your nature-inspired security blanket.
Below are my suggestions for the best cloud-watching spots at the Arboretum:
- Highpoint (The Harrison Sculpture Garden)
- The Dog Commons
- The Overlook at the Tashjian Bee and Pollinator Discovery Center
- The Bennett-Johnson Prairie
My suggestions for a cloud-watching kit:
- A blanket to sit on
- A pillow to rest your head on
- A picnic basket full of yummy snacks
- A thermos full of coffee, tea or lemonade — depending on the weather
- Sunglasses — clouds are great to look at when you’re not blinded by the rays
- A friend to share the experience with
- A notebook, pen and colored pencils to illustrate what you’re seeing and write down thoughts or even a cloud haiku:
Clouds give time to pause,
Like thoughts, emotions, they pass.
We share the same sky.
Dr. Jean Larson is the manager of Nature-Based Therapeutics and Nature Heals Initiative at the Minnesota Landscape Arboretum and is faculty lead of the Nature-Based Therapeutic Studies at the Earl Bakken Center for Spirituality and Healing of the University of Minnesota.
Cover photo by Sara Pace