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Salem Clock Shop - 1085 Broadway Street NE, Salem, OR 97301 - (503) 581-3803 Fax: (503) 581-3331 |
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You can learn how clouds form by experimenting with a few simple items. |
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Making a Cloud in a Jar |
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· Place the ice in the metal dish. · Let it stand until it gets very cold. · Once the dish is cold, place 1 inch of warm water in the jar. · Place the metal dish over the top of the jar. · As the warm water evaporates, it will encounter the cold dish. · The moisture will then condense and form a cloud.
WHAT HAPPENS IN NATURE
Warm air at the ground is lighter and less dense than the surrounding air above, so it begins to rise. The rising air takes on the shape of a round bubble.
Several things happen as the bubble rises up through the atmosphere; as the pressure on the air bubble drops, the bubble expands and increases in size. Anytime air expands due to a drop in pressure, it also cools. These masses cool at a rate of approximately 5.5 degrees F per 1000 feet of rise. This is called the dry adiabatic lapse rate.
As warm air is able to hold larger amounts of water vapor than cool air, the cooling parcel is no longer able to hold as much as it did. The excess water vapor begins to condense out of the air as droplets. When water vapor begins to condense into liquid droplets, this means the air mass is saturated and has reached its dewpoint temperature.
The rising, expanding & cooling air finally rises so high that the surrounding atmospheric air is the same temperature as the cooled bubble. This is called the equilibrium temperature. When equilibrium is reached, the air mass loses momentum and stops rising.
By the time the air mass has reached equilibrium temperature, enough moisture will have condensed out of it to form a visible cloud!
Cloud heights and shapes vary according to the atmospheric conditions. On a hot day, clouds will tend to form at higher altitudes, because the rising air bubbles must rise higher in order to cool sufficiently to reach dewpoint.
When air masses continue to rise after dewpoint has been reached and condensation has occurred, the cloud becomes very tall. This is how cumulus and cumulonimbus clouds form. If air masses only rise a short distance over a large geographical area after reaching dewpoint, layer clouds (such as stratus) will form.
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Bill of Materials
· Mayonnaise jar or similar · Metal dish · Ice · Warm water
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Warm Ground |
