Chapter 7Lesson 4

How do clouds form?

Make a cloud demonstration• Demonstrate cloud formation with a large,

wide-mouthed jar, a match, a cup of very warm water, a rubber band, and a plastic bag.

• Pour the water into the jar. • Drop a lit match into the jar, then quickly cover

it with the plastic bag. • Secure the bag on the lid with a rubber band. • Push the bag into the jar, and pull it out again.

A cloud will form. • Ask: How did the match help form a cloud?

Why do you need to secure the plastic bag onto the jar?

Clouds are made of:•water vapor or ice crystals - depends on temp. & air pressure

Activity- How many drops of water can a cloud hold?I predict that the cotton ball will hold _____ drops of water before it overflows.

Result: The cotton ball held ___ drops before it overflowed.

Clouds and Drizzle [02:37]

Types of cloudsCloud Where it forms Description

cirrus > 6,000m above ground

High altitude, thin, wispy & white

cumulonimbus

thunderhead

Base-1,000m above ground

Top-12,000m above ground

Vertical

cause thunderstorms

cumulus Base-2,000 -7,000 m above ground

Mid-altitude, puffy

stratus <2,000m above ground

Low altitude

Dark, cover sky

fog Ground level Forms b/c air cools

Types of Clouds [02:34]

Types of clouds-YouTube

NASA: Our World: Cool Clouds

Types of Clouds-

Types of precipitationForm of

precipitationHow it forms

rain If ice crystals fall in air > 0 C melt

freezing rain Ice storm-rain freezes when hits cold object

sleet Frozen raindrops

snow

hail

snow

• Ice crystals high in atmosphere grow larger snowflakes

snow

hail• Forms when strong winds blow

upward into cloud repeatedly

• Made up of layers of ice by updrafts

• Circulates in cloud-too heavy & falls

• Small frozen raindrop that gets caught in updrafts

hail

YouTube video-How does hail form

Precipitation [02:21]