Photo credit – David Walker
The high etage (over 20,000 feet) has a stratiform cloud type, just as the lower two do. Like the other layer clouds, cirrostratus forms in stable air with a high moisture content. Cirrostratus, along with cirrus and cirrocumulus, is often a harbinger of approaching weather. As warm air overtakes and slides up over cold air it creates the formation known as a warm front. The cirrus clouds lead the way at the highest extent of the warm, moist air. As the front approaches, we get progressively lower clouds until the front passes. It will be warmer then, but most likely wetter, too.
Photo credit – Daniele Massaccesi
Photo credit – John Rowlands
Photo credit – Jane George
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