ROLL CLOUD OVER PORTUGAL

CURRENT CONTEXT  : A rare roll cloud was observed along the Portugal coast, during a severe heatwave.

 About Roll Cloud

• Type: A rare form of arcus cloud
• Appearance: Low, horizontal, tube-shaped cloud that appears to “roll”
• Altitude Range: Typically forms between 2,000–7,000 metres
• Formation Conditions: When cool air undercuts warm moist air, especially along gust fronts or sea breeze fronts
• Not Tornado: Unlike funnel clouds, it does not touch the ground
• Occurrence Regions: Coastal/mountainous areas – e.g., Japan, Alps, Scotland, northern Australia
• Weather Significance: May indicate upcoming thunderstorms or wind shifts

 What is an Arcus cloud?

• Definition: A cloud formation on the leading edge of a thunderstorm outflow
• Types:
• Shelf Cloud (attached to parent storm)
• Roll Cloud (detached from storm system)