CLOUD ATLASby Michal Lumsden and Meggie Winchell
| Fair weather cumulus clouds form when a parcel of air rises and water vapor
condenses into water droplets.
|This is a classic case of stratus clouds. The sky has a sheet-like grey covering and the sun is not visible.|
|Stratocumulus clouds form a clumpy layering across the sky. They are not as well- defined or as well-separated as fair weather cumulus clouds are.|
|There are times at dusk when sunlight shines through the breaks in the stratocumulus covering. The effect is often call “Jesus Rays” however the formal name is crepuscular rays.|
|Altostratus is a uniform light grey layer covering the sky. Usually the sun is dimly
through these clouds.
|2.2 a. Altocumulus as stripes.||b. Altocumulus in uniform puffs.|
|On sunny days you can often see white wispy clouds that look high in the sky. These are cirrus clouds. Their wispiness is caused by the fact that when their ice crystals get spread out by the wind they don’t evaporate right away. We see the trails of ice crystals as streaks of white in the sky. Because of this wispiness cirrus clouds are sometimes called “mares’ tails.”|
|Cirrocumulus is similar to altocumulus, however the puffs are higher and appear smaller. If you reach your hand out towards the sky a single cirrocumulus cloud will be about the size of your pinky-tip. Like altocumulus these clouds can form a uniform pattern or rows. Since these clouds can look like fish scales a cirrocumulus covering is sometimes called a “mackerel sky.”|
|A single ice crystal is hexagonal and very small—about 10 micrometers in diameter. The arrangement of these ice crystal and their interactions with sunlight can produce halos, sundogs, and sunpillars.|
|3.2 an ice crystal|
|Halos are produced when sunlight passes through randomly oriented ice crystals. If you extend your arm and put your thumb on the sun, the halo will most likely be at your pinky- tip.|
|When light passes through ice crystals that are uniformly oriented, sundogs can form. These are colorations about a thumb-to-pinky distance on either side of the sun.|
|Sometimes when the sun is low in the sky a sunpillar can be seen. A sun pillar appears as a shaft of light extending above or below the sun. It occurs when light is reflected off uniformly oriented ice crystals which tilt as they fall.|
|Nimbostratus clouds are low-lying clouds with no clear base. They produce continual
precipitation, usually drizzle or snow.
4.2 a. Towering Cumulus:
Due to continuous warming
and accelerated rising, fair weather cumulus grows taller and becomes towering cumulus clouds.
b. Developing Cumulonimbus:
The updrafts become stronger and the clouds grow darker and larger.
c. Mature Stage:
In the mature stage of a
thunderstorm water droplets grow and fall as precipitation. There are also violent updrafts and downdrafts throughout the thunderhead.
|Double rainbows occur when there are two reflections within the same water droplet.|