(WC) Experiencing Weather Lesson
Experiencing Weather
Weather affects how you dress and how you plan your day, so it is important to get accurate weather forecasts.
A weather forecast is a prediction of weather conditions over the next 3 to 5 days.
A meteorologist is a person who observes and collects data on atmospheric conditions to make weather predictions.
Clouds
Clouds can come in all sizes and shapes, and can form near the ground or high in the atmosphere. Clouds are groups of tiny water droplets or ice crystals in the sky and are formed by different processes. They can make different kinds of precipitation depending on the atmosphere's temperature.
Meterologists classify clouds into three main types: cumulus, stratus, and cirrus. Cloud types are classified by height and appearance. The shape depends on the way the air moves around the cloud. If air moves horizontally, clouds form spread-out layers. Clouds grow upward if air is moving vertically near the cloud.
At any given time, clouds cover about 50% of the Earth. We would not have rain, thunderstorms, rainbows, or snow without clouds. Clouds make up some of the atmospheric optics we can see in the sky. The atmosphere would be boring if the sky was always clear!
Clouds form when water vapor in the air becomes liquid water or ice crystals, through condensation.
Cloud Types
Clouds are classified into a system that uses Latin words to describe the appearance of clouds as seen by an observer on the ground. The table below summarizes the four principal components of this classification system (Ahrens, 1994).
| Latin Root | Translation | Example |
|---|---|---|
| cumulus | heap | fair weather cumulus |
| stratus | layer | altostratus |
| cirrus | curl of hair | cirrus |
| nimbus | rain | cumulonimbus |
Classifications:
High-Level Clouds
Cloud types include: cirrus and cirrostratus.
Mid-Level Clouds
Cloud types include: altocumulus, altostratus.
Low-Level Clouds
Cloud types include: nimbostratus and stratocumulus.
Clouds with Vertical Development
Cloud types include: fair weather cumulus and cumulonimbus.
Other Cloud Types
Cloud types include: contrails, billow clouds, mammatus, orographic and pileus clouds.
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