Definition

1. Noun:
   • A mid-level cloud formation: An altocumulus cloud is a type of cloud belonging to the middle cloud family, typically found at altitudes between 6,500 and 20,000 feet (approximately 2 to 6 kilometers).
   • Characteristic appearance: It appears as a layer or patch of white or gray clouds, composed of rounded masses or rolls, often arranged in groups, lines, or waves across the sky.

Usage

• Altocumulus clouds are often indicators of atmospheric instability at mid-levels.
• They are primarily composed of water droplets and can sometimes contain ice crystals.
• Observing altocumulus clouds can help in short-term weather forecasting.

Examples

• Noun:
  • The sky was dotted with a fleet of altocumulus clouds this morning.
  • Meteorologists noted that the altocumulus cloud layer suggested a change in the weather pattern.
  • The altocumulus cloud formation created a beautiful, textured pattern against the blue sky.

Advanced Usage

• "Altocumulus castellanus": A specific subtype where cloud towers rise from a common base, resembling castle battlements. This type often indicates greater instability and can precede thunderstorm development.
  • The presence of altocumulus castellanus suggested the possibility of afternoon thunderstorms.
• "Altocumulus lenticularis": A lens-shaped, stationary subtype often formed by mountain waves, sometimes mistaken for "flying saucers".
  • The altocumulus lenticularis clouds remained fixed over the mountain peak.

Variants and Related Words

• Altocumulus (n): The standard, shortened form of "altocumulus cloud". Often used interchangeably in meteorological contexts.
  • The forecast calls for altocumulus and high winds.
• Ac (abbreviation): The standard meteorological abbreviation for altocumulus clouds.
  • The weather map showed a large area marked 'Ac'.

Synonyms

• Mid-level cumuliform cloud: A descriptive synonym emphasizing its form and altitude.
• Sheepback cloud: An informal, descriptive term sometimes used due to its woolly, flocked appearance.

Related Phrases

• A mackerel sky: A common phrase describing a sky filled with altocumulus clouds in a pattern that resembles fish scales, often a sign of an approaching warm front.
  • "Mackerel sky, mackerel sky, never long wet and never long dry," is an old saying referring to altocumulus clouds.

Noun

1. a cumulus cloud at an intermediate altitude of 2 or 3 miles