Unlike the Bergeron Process, where precipitation forms under supercooled conditions, the Collision and Coalescence Process typically occurs within relatively warm clouds with tops warmer than -15C.

What kind of cloud would be most likely described by the collision-coalescence process? The Bergeron process describes precipitation from the top of cumulonimbus clouds, while the collision-coalescence theory describes precipitation from nimbostratus.

Coalescence is the process by which two or more droplets, bubbles or particles merge during contact to form a single daughter droplet, bubble or particle. As droplets are carried by the updrafts and downdrafts in a cloud, they collide and coalesce to form larger droplets.

cumulus cloud

The difference between the cold parcel air and the warmer surroudings gets larger and larger with increasing altitude. Sunlight warms the ground and the air next to it during the day. This steepens the environmental lapse rate and makes the atmosphere more unstable. Cooling air above the ground has the same effect.

The presence of stratus clouds usually means a chilly, overcast day. If precipitation falls from stratus clouds, it is usually in the form of drizzle or light snow.

When the clouds get full of water that they can’t hold anymore, the water falls down as rain. In this experiment, the clouds are the shaving cream and the food colored water is the rain. As you drop the colored water into the cloud the weight of the water forces itself through the cloud to “rain” down into the jar.

There are ten main types of clouds:

• Altocumulus.
• Altostratus.
• Cirrocumulus.
• Cirrostratus.
• Cirrus.
• Cumulonimbus.
• Cumulus.
• Nimbostratus.

The 1956 act took a long time to become effective, but it worked: Another great yellow fog in 1962 was the last. Since then, despite the belief in some parts of the world — not least the United States — that there are still foggy days in London town, pea soupers have become a thing of the past.

San Francisco

Fog is caused by tiny water droplets suspended in the air. The thickest fogs tend to occur in industrial areas where there are more pollution particles in the air allowing water droplets to coalesce and grow.

Long, cool autumn nights cause the air near the ground to chill, causing the formation of fog to be prevalent in fall. Fog is most likely to occur at night or near dawn when the temperature of the day is normally at it’s lowest.

Washington

When the air near the ground cools to dew point, the water vapor in the air will become visible as fog in the air or dew on the ground. During the summer when the sky is clear and the humidity is near 100 %, fog will form. During fall and early winter the most common form of fog is Radiation Fog.