LESSON 2 - THE WEATHER

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Objectives
Materials
Background Information
Key Questions
Vocabulary
Procedure
Evaluation

Objectives

  • Students will identify the different elements that make up earth's weather.
  • Students will compare four types of clouds.
  • Students will identify the type of weather associated with each type of cloud.
  • Students will investigate weather elements using hands-on and collaborative problem solving.
  • Students will construct an observation sheet.

Materials

Background Information

Water is everywhere. It can be found in many places and many different forms. Most of the water found on Earth is in oceans and the polar ice caps. You can also find water in clouds, rain, rivers, ponds, and sea ice. Water constantly moves through the water cycle by means of evaporation, precipitation, and runoff.

Clouds are visible masses of water droplets that have condensed or are composed of ice crystals that are suspended in Earth's atmosphere. The condensed water vapor will form small water droplets or if it is cold enough, ice crystals which, when they become surrounded by billions of other water droplets or ice crystals, become visible as clouds.

Invisible water vapor becomes visible when it is cooled. This is what you see on a cold winter day when you can see your breath as you exhale. Warm moist air leaving your mouth is cooled and condenses to form a collection of visible droplets. The same thing happens when water is boiled on a stove. Warm air rises above the boiling water and cools to form water vapor that we call steam. Fog is a cloud that is in contact with or very close to the ground. Fog occurs when moisture from the ground evaporates. As the moisture moves up, it cools down and condenses into fog. There are many events which causes air to rise and cool and form clouds. Mountains force air upwards. This air that is forced up and over the mountain cool to form clouds. Another example is a cold air mass that lifts and cools the air ahead of it. Air that is heated by the sun rises higher in the atmosphere, cools, and clouds are formed. Heat from the sun has enough lifting power to produce thunderstorms.

A majority of water droplets form when condensed water vapor condenses around some form of particulate matter which could be smoke, ash, dust, or salt. If the cloud is supersaturated, water droplets can even become particulate matter.

There are four major cloud types:

Cumulus clouds individual clouds that resemble puffs, towers or mounds, and have flat bases and tops that looks like cauliflower. They are formed due to convection, ie buoyant upward air currents known as thermals whenever the air can rise to a height at which its moisture can condense. Though most common in warm, summer weather, cumulus clouds can be formed at any time of year.

Cumulonimbus is a type of cloud that is tall, dense, and involved in thunderstorms and other bad weather. The clouds can form alone, in clusters, or along a cold front in a squall line.

A Stratus cloud is characterized by horizontal layers that have an even base that varies from very dark gray to almost white. Stratus clouds are basically fog that is found above ground level and they are formed when fog lifts in the morning or when colder air is moving along low altitudes. These clouds generally don't produce rain, but mist and drizzle may occur.

Cirrus clouds are made up of tiny ice crystals and are shaped like hair filaments. They form at altitudes around 16,500 feet and above. The presence of a lot of cirrus clouds could indicate the approach of a frontal system. Cirrus clouds are also the leftovers of thunderstorms.

Collection of precise data is needed to make accurate local weather forecasts.

Listed below are some general guidelines to help your students begin to make accurate weather observations.

  1. Establish an observation schedule to identify weather trends and changes.
  2. Use weather instruments.
  3. Record weather data on a chart.

Key Questions

  1. What are the key elements that make up weather?
  2. What are the four cloud types?
  3. What are some weather conditions associated with the different cloud types?

Vocabulary

  • clouds
  • precipitation
  • temperature
  • wind
  • cirrus
  • cumulus
  • stratus
  • cumulonimbus

Procedure

1. Take your students outside with pencils and pads and have them safely observe how clouds move. Instruct your students to never look directly at the sun. If cumulus clouds are present, your students can watch as they change shape. Have your students enter their data on the cloud observing form.

2. When you return to your classroom, discuss the various clouds that your students sketched. Direct your students to the internet to compare their cloud drawings with pictures of the different cloud types. You may want to post a cloud chart or transparency of different cloud types. Your students should understand there are four main cloud types and recognize the symbols that are used for each.

This internet site may be helpful:

http://commons.wikimedia.org/wiki/Cloud

3. Discuss cloud formation and cloud types as a class.

Cloud formation image (NOAA)

Use the following experiment to demonstrate cloud formation and discuss the various elements that are involved in weather.

Materials:
one gallon jar
warm water
plastic bag of ice large enough to cover the mouth of the jar
black construction paper
several wooden matches
flashlight

Preparation: Tape the paper to the back of the jar. Fill one-third of the jar with the warm water.

Procedure: Light two or three matches, blow them out and as they are still smoking, drop them into the jar. Quickly cover the opening of the jar with the ice bag. Shine the flashlight into the side of the jar and watch as the cloud begins to form.

Discuss the process that led to the formation of the cloud in the jar. Ask your students why smoke was important to the formation of the cloud. Restate that the sun heats up the air and when air rises, it cools and forms clouds.

Divide your class into groups and assign each group a specific cloud type to draw, color, and label. Hang the drawings from the ceiling to create your own classroom sky.

4. Explain that many weather patterns are associated with distinctive cloud types.

Have your students conduct a study on the specific weather patterns that are associated with distinctive cloud features. Each student should keep a daily observation chart to record precipitation, temperature, and cloud patterns for a period of three days. Have your students use the internet sites listed in the Student's pages to gather their data.

After your students have gathered the materials and knowledge required to record temperature, take precipitation readings, and cloud observations, they will begin their observational study. The students will focus on the following question: What specific weather patterns are associated with which cloud types?

Students will use the following headings to chart their data:

Temperature, Cloud Type, Precipitation, Weather Pattern Associated

Internet sites are listed in the Students pages for this lesson to help them gather their data.

When the students have collected all of their data and entered it into their charts, they will write a report interpreting their data. Begin a discussion based on which weather patterns are associated with which cloud types.

Restate that weather is simply the condition of the air that is around us. Meteorologists use cloud types, temperature, precipitation, and wind direction to forecast the weather.

Evaluation

Using the charts that were constructed to compare daily cloud and weather patterns, your students will write a report explaining cloud cover, temperature, cloud types, precipitation, temperatures, and the weather conditions most commonly associated with the data collected. The students should graph and interpret their data. Have your students share their reports with the class.

Students can also compare their local weather observations with daily forecasts from the newspaper or television.

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