With the celebration of the 50th anniversary of the Apollo moon landing this year, the United States is once again looking up to the sky and the stars. But what about the sky closer to home, the one that we see every day? Meteorology studies weather patterns and the different types of clouds that cover the sky every day, but most people don’t know the names of these clouds or pay attention to what they can signify for the weather. Below are the names of the clouds in the sky, where they’re located and just what they represent for your weather forecast.

High-Altitude Clouds

In the highest altitude of the sky, you have four main types of clouds: cirrocumulus, cirrus, cirrostratus and cumulonimbus.

Cirrocumulus clouds are usually white, but sometimes gray, and are very small. When there are a lot of them, the sky can look like fish scales (commonly known as a mackerel sky). They’re most common in winter and tend to show cold but fair weather. Cirrus clouds are the most common high-altitude clouds and are thin and wispy. They tend to foretell fair weather and can reveal the direction of the wind at their elevation. Cirrostratus clouds are high and thin, looking like sheets that cover the sky. They are so thin that the sun and moon can shine through them, creating a halo. These clouds tend to come 12-24 hours before snow or rain. The last high-altitude clouds, cumulonimbus, are harbingers of heavy rain and thunderstorms and even lightning. They are the lowest of the altitude clouds and are also called thunderheads due to their mushroom-like shape. The rain they produce is heavy but short.

Mid-Altitude Clouds

In the mid-altitude range you have two different types of clouds: altocumulus and altostratus.

Altocumulus clouds look like gray puffballs and tend to appear in groups. If you see them on a warm humid morning, thunderstorms will be coming in soon. The other kind of mid-level cloud cover, altostratus clouds, are dark blue or gray clouds that cover the whole sky in a thick sheet. If the sun or moon shines through, it will be watery or fuzzy light; if these appear, continuous snow or rain may be on its way.

Low-Altitude Clouds

Finally, there are three low-level cloud types: stratus, cumulus and stratocumulus.