Clouds, Thunder & Light
Explain Today's Lesson
Body of the Lesson
|Student becomes aware of clouds on a new level. No longer views them as just interesting shapes or fluffy white things in the sky. Student understands not only they clouds bring rain, lightning and thunder but will know how these things happen.|
|Learners & Context|
|Room Setup||Media Used|
|Standard elementary school science classroom equipped with a computer with internet access connected to an overhead projector|
|To Bring||To Do Ahead|
|Experiment Materials small paper bag(s) 2 balloons pocket comb(s) box of puffed rice cereal roll of cloth friction tape||Rehearse the experiments to make certain they work.|
Prior Knowledge Activation & Motivation: Instructor reminds class of their work last time with clouds. Today we'll be learning about the different kinds of clouds and how they behave. Clouds build up and result in storms, thunder and lightning. Later today we'll be creating a little of our own thunder and lightning here in the classroom.
Explain Today's Lesson
Overview: The main principles and theories of the days lesson are touched upon. a) There are several types of clouds b) Air masses moving past each other produce friction resulting in static electricity. c) Static electricity dissipates in sparks. d) Clouds build up static electric charges. e) The giant static electric sparks from clouds are what we call lightning. f) Lightning discharges cause thunder.
Body of the Lesson
a) Here are the basic cloud types Cumulus are puffy mid-level white clouds made of water and ice, usually associated with fair weather. Cirrus are high wispy clouds made of ice, also occurring with fair weather. Stratus are flat low clouds made of water which sometimes produce light rain or drizzle (fog is a stratus cloud). Nimbostratus clouds are thick dark low-level clouds that can produce rain or drizzle. Cumulonimbus clouds (thunderheads) are deep dark and puffy clouds that often produce thunderstorms. Clouds form when water vapor rises, cools, and condenses. b) Air masses moving past each other (wind) cause friction in the atmosphere. Air moves because of differences in air pressure. When a low pressure area exists, high pressure air want to move in, fill up the space and spread out. Like the way water from a narrow stream spreads out in a wide area to form a pool. As the air masses pass each other the gas and vapor molecules bump into each other and knock loose some electrons. The newly free electrons look for a new places to attach but keep bumping into molecules that have no open spaces. (We see this with magnets too. That's why these are called electro-magnetic forces. Which indicates that magnetism and electricity are somewhat related. Both depend on the attraction and movement of electrons.) High pressure air moving into an area of low pressure air can bring cold air into contact with warmer air. When cold air meets warm air, the cold air sinks and digs under the warm air, forcing it to rise quickly. The rising air takes water vapor with it, which cools and condenses, forming cumulonimbus clouds, sometimes called thunderheads. d) When water droplets and ice particles bang together in the cloud, they help build up positive and negative electrical charges. Positive charges gather near the tops . and bottoms of the clouds. Negative charges gather in the middle.(e)The negative charges are attracted to the positive charges at the bottom of the cloud and on the ground. Electricity flows between them in the form of lightning. (f) Lightning heats the air around it. The heat causes the air to expand suddenly with explosive force, resulting in a loud sonic boom we call thunder.
Students are presented with the experiment guidelines and are asked to hypothesize as to what will happen and why. Guidelines include setting up and conducting the experiment and recording the results. Afterwards they will be asked to form conclusions from their observations. For the activities listed below students can work in small groups. Each demonstrating their activity to the others. Thunder & Lightning Experiments: Materials needed per group: small paper bag(s) 2 balloons pocket comb(s) box of puffed rice cereal roll of cloth friction tape Making Thunder: Each child is told that thunder is a sound that occurs when an air mass moves very rapidly from one location to another. The heat produced by a lightning flash causes a sudden and rapid expansion and movement of air. You will do much the same using a paper bag. Inflate the paper bag, twist it closed. Now smack it hard with your other hand. What happened in term of the air rushing suddenly out of the bag? Source: Weather Dude web site Making Lightning: Option 1: Inflate two balloons and rub them vigorously on your clothes. In a darkened room bring the two balloons together slowly. Sparks should occur between them. Theorize as to why the sparks were produced. Option 2: Rub a comb through your hair again and again. Now put the comb on a small pile of puffed rice cereal. The grains will stick to the comb. Theorize as to why they stick. Option 3: In a darkened room unroll a roll of friction tape. Try both fast a slow movement. Theorize as to why sparks are produced. Students answer questions or complete a questionnaire: Was the hypothesis correct? If yes, why? If no, why not?
Summary: Students reform as a large group and report the result of their experiments with the prompting of their instructor and the instructional website. Remotivation: Congratulates the students on the success of their experiments and on their conclusions. Instructor summarizes the main points of the lesson.
Instructor asks them to think about how storms affect society. The next lesson will cover violent storms, what to do to avoid being by lightning. And how weather shapes land forms and societies. Instructor tells the class the lesson is over.