What is graupel?

Graupel: Soft Hail

Graupel is a form of precipitation that occurs when supercooled water droplets (water colder than 0°C but still liquid) collect on a snowflake, forming a soft, crumbly pellet. It is sometimes referred to as snow pellets or soft hail.

Formation:

• It starts as a snowflake falling through the atmosphere.
• The snowflake encounters supercooled water droplets.
• These droplets freeze onto the snowflake, accumulating and forming a soft, rounded mass.
• Unlike hail, graupel is not made of layers of ice.

Characteristics:

• Size: Typically 2–5 mm in diameter.
• Texture: Soft, crumbly, and easily compressible.
• Appearance: White and opaque, sometimes resembling small snowballs.
• Density: Less dense than hail.
• Impact: Often disintegrates upon impact with the ground.

Distinguishing Graupel from Hail:

• Hail is harder, more dense, and often layered. Hail is also usually larger than graupel.
• Graupel is softer, more easily crushed, and does not have distinct layers.

Weather Conditions:

• Graupel often occurs during convective snow showers.
• It can be an indicator of unstable atmospheric conditions.
• Sometimes it precedes or accompanies more intense winter weather.

Hazards:

• Graupel can reduce visibility while driving.