Clouds, Precipitation, and Fog

Summary

This lecture discusses clouds, precipitation, and fog, focusing on their formation and types. It explains how clouds are made of tiny moisture droplets or ice crystals, and highlights cloud identification through shape (stratiform, cumuliform, cirriform) and altitude (low, middle, high). Cumulonimbus clouds, which can lead to violent weather, are also covered. The lecture explores precipitation as liquid or solid water falling from clouds and its process of coalescing into larger drops. Additionally, it explains different fog types like advection fog, which forms over cooler surfaces, and radiation fog, such as California's Tule fog, which has decreased due to improved air quality.

Takeaways

• 😀 Clouds are visible groups of moisture droplets or ice crystals suspended in the air.
• 😀 Fog is essentially a cloud on the ground, indicating that the air at ground level is saturated.
• 😀 Precipitation is liquid or solid water that falls from clouds, including rain, snow, and hail.
• 😀 Condensation occurs when the air is saturated, and takes place around a condensation nucleus, such as dust or pollution particles.
• 😀 Clouds can be classified by shape (stratiform, cumuliform, cirriform) and altitude (low, middle, high).
• 😀 Cumulonimbus clouds are vertical formations that can produce violent weather, including thunderstorms.
• 😀 Low clouds occur from the surface to 6,500 feet, mid-level clouds range from 6,500 to 20,000 feet, and high clouds are above 20,000 feet.
• 😀 Precipitation forms when small droplets in clouds collide and coalesce into larger droplets, which then fall as rain or snow.
• 😀 Advection fog forms when warm, moist air moves over cooler surfaces like oceans or lakes, commonly seen on subtropical coasts.
• 😀 Radiation fog forms on clear nights when the ground cools, chilling the air layer above it to the dew point, leading to dense fog, especially in valleys like California's Central Valley.

Q & A

What is the basic definition of a cloud as explained in the script?

A cloud is a visible group of moisture droplets or ice crystals that are suspended in the air.

How is fog different from clouds?

Fog is essentially a cloud that forms at the ground level, indicating that the air at ground level is saturated.

What is the role of condensation nuclei in cloud formation?

Condensation nuclei are microscopic particles, like dust or soot, around which condensation occurs in the atmosphere, helping to form clouds.

What are the three main types of clouds based on shape?

The three main types of clouds based on shape are stratiform (flat and layered), cumuliform (puffy and globular), and cirriform (wispy and high-altitude).

How are clouds classified based on altitude?

Clouds are classified into low clouds (up to 6,500 feet), mid-level clouds (6,500 to 20,000 feet), and high clouds (above 20,000 feet).

What is a cumulonimbus cloud and why is it significant?

A cumulonimbus cloud is a vertical cloud formation that can cause severe weather, such as thunderstorms, and is associated with cyclonic storms.

How does precipitation occur, according to the script?

Precipitation occurs when enough condensation takes place, causing small droplets to collide and coalesce into larger drops. When these drops become too heavy, they fall as rain, snow, or hail.

What are the two main types of fog discussed in the lecture?

The two main types of fog discussed are advection fog, which occurs when warm, moist air moves over a cooler surface, and radiation fog, which forms when the ground cools and chills the air layer above it.

What is Tule fog and why is it notable?

Tule fog is a type of radiation fog that forms in California's Central Valley during winter. It is notable because there has been a significant decrease in its occurrence due to improved air pollution controls in the region.

How does the decrease in air pollution affect fog formation in California?

The decrease in air pollution leads to fewer condensation nuclei in the atmosphere, reducing the formation of fog, especially Tule fog, which relies on these particles for condensation.