Cavum Clouds
Source: Hindustan Times
GS I: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location- changes in critical geographical features (including waterbodies and ice-caps) and in flora and fauna and the effects of such changes.
Overview
- News in Brief
- What is Cavum Clouds
- What are Altocumulus Clouds?
Why in the News?
NASA’s Terra satellite, ice crystals in the hole’s centre form wispy streaks of precipitation that do not hit the ground.
News in Brief
- NASA shared a photograph showing what are seen as ‘odd holes’ in the clouds above the Gulf of Mexico and off the coast of Florida.
- Ice crystals falling at the centre of the holes appear as delicate streaks of precipitation that never reach the ground.
- These are known as virga resembling rain or snowfall from clouds but evaporating before reaching the surface.
- NASA scientists have long speculated about these clouds, referred to as cavum clouds.
What is Cavum Clouds
- Also known as hole-punch clouds or fallstreak holes.
- These are caused by aeroplanes.
- Cavum clouds form when planes fly through banks of altocumulus clouds, mid-level clouds with supercooled (below the freezing point of water but still liquid) water droplets.
- As air moves around the plane, adiabatic expansion (A process without transfer of heat to or from a system) can make the droplets freeze into ice crystals.
- The ice crystals eventually grow heavy and fall out of the sky, leaving a hole in the cloud layer.
- There are holes in the clouds in some areas, exposing the blue and turquoise ocean water underneath.
What are Altocumulus Clouds?
- Altocumulus clouds are mid-level clouds that typically form between 6,500 to 20,000 feet (2,000 to 6,100 meters) above ground level.
- They are characterized by their layered or patchy appearance and often resemble a field of cotton balls or fish scales.
- Altocumulus clouds are composed of water droplets and occasionally ice crystals, depending on the temperature at their altitude.
Key Facts and Features
- Appearance: Altocumulus clouds usually appear as white or grey patches or layers of cloud with rounded edges. They may form in groups, lines, or waves across the sky.
- Composition: These clouds are primarily made up of water droplets, although at higher altitudes, they may contain ice crystals.
- Altitude: Altocumulus clouds typically form at mid-level altitudes, between 6,500 to 20,000 feet above the ground. They are found above lower-level cumulus clouds but below higher-level cirrus clouds.
- Weather Patterns: Altocumulus clouds are often associated with fair weather, but they can also indicate changes in the atmosphere. If altocumulus clouds thicken and lower, they may develop into altostratus clouds, which can precede precipitation.
- Area of occurrence: Altocumulus clouds are commonly observed in temperate and tropical regions around the world. They can form in various weather conditions but are frequently seen during stable weather patterns.
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