The Mystery of Lightning By Kendra Wheeler LTEC 4100.031
TEKS Objectives 112.18 Science: Grade 6 (a) Introduction. (1) Science, as defined by the National Academy of Science, is the "use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process." This vast body of changing and increasing knowledge is described by physical, mathematical, and conceptual models. Students should know that some questions are outside the realm of science because they deal with phenomena that are not scientifically testable. (4) The strands for Grade 6 include: (A) Scientific investigations and reasoning. (b) Knowledge and skills (2) Scientific investigation and reasoning. The student uses scientific inquiry methods during laboratory and field investigations. (E) analyze data to formulate reasonable explanations, communicate valid conclusions supported by the data, and predict trends.
What Is Lightning? • Lightning is an atmospheric discharge of electricity. • It is the same kind of electricity that can happen when an object or person shocks you, which is commonly known as static electricity. • The majority of lightning happens within the cloud or between the cloud and ground.
How Does it Work? • Electrical charges produce inside of a storm cloud. • The negative charges moves to the bottom of the cloud, while the positive charges moves to the top. • When the area for the negative charge becomes crammed, then the atoms “spring” to another section of that cloud, or the ground, or even to different cloud. • This “spring” causes a massive spark of static electricity that is known as lightning.
How Does It Work Cont’d… • When there is a huge charge separation in the electric area around the cloud, it will then begin to break down the air and cause the space that is sandwiched between the protons and electrons to expand in size. This method is known as ionizing the air. • The ionization causes several paths that are known as step leaders. Their job is to find the easiest way to the opposite charge. • As a place prepares for an electrical discharge, the positive area on the ground will send out a streamer that signals to the step leaders as being one that is positively charged and is an easy route. • The last stage is the step leader and the streamer coming together, which is a complete path of ionized air connecting the ground and the cloud. When they two cross paths, it causes a current that is called the first return stroke. The first return stroke is the ‘lightning’ that we see light up the sky.
Different Types of Lightning • Cloud-to-Ground lightning: is a discharge between a cumulonimbus cloud and the ground. • Ground-to-cloud lightning: is a discharge between the ground and a cumulonimbus cloud. • Forked lightning: is a type of cloud-to-ground lightning that displays branching.
Types Of Lightning Cont’d • Ribbon lightning: occurs in thunderstorms with high cross winds and multiple return strokes. The wind will blow each successive return stroke slightly to one side of the previous return stroke, causing a ribbon effect. • Bead lightning: is a type of cloud-to-ground lightning which seems to look as if it has broken up into a series of short, bright parts. • Ball Lightning: looks to be a glowing sphere that is recorded to be less than three feet wide and doesn’t last more than a couple of minutes.
Essential Question • What are some of the different types of lightning and how does lightning form?
Unit Questions • In a storm cloud, what type of charges are at the top and bottom of the cloud? • What type of lightning is only three feet wide and only last for a couple of minutes? • Where does the majority of lightning happen? • When an object shocks a person, is that the same kind of electricity as lightning?
Fun Activities From D.E. Materials: • Group 1: ground pepper; plastic utensil, such as a knife or a comb; wool or nylon cloth • Group 2: plastic comb, piece of wool or fur, metal doorknob • Group 3: two rubber balloons • Group 4: plastic combs, bowl of puffed rice Procedures: • Group 1: • Spread grains of ground pepper on a small area of a desktop. • Vigorously rub a plastic utensil with a wool or nylon cloth to produce a negative charge. • Hold the utensil about 1 inch over the mixture and observe what happens. (The utensil will pick up the pepper.) • Group 2: • Darken the room as much as possible. • Rub a plastic comb with a piece of wool or fur. • Hold the comb near a metal doorknob. • Observe what happens. (Students will see tiny sparks.) • Group 3: • Blow up two balloons and rub them on your sleeve. • Darken the room as much as possible. • Rub the two balloons together. • Observe what happens. (Students will see tiny sparks.) • Group 4: • Run a comb through your hair (only one student should use each comb). • Put the comb into a bowl of dry puffed rice. • Observe what happens. (Grains of rice will stick to the comb; after they lose their charge, they will fall off.) *After the experiments, students will then write a paragraph and a draw diagram describing their group’s experimentation.
Credits and References National Geographic -http://news.nationalgeographic.com/news/2004/06/0623_040623_lightningfacts.html National Weather Service-http://www.lightningsafety.noaa.gov/more.htm 2003 Flight Forecast-http://www.centennialofflight.gov/2003FF/lightning/types.html TEKS-http://www.tea.state.tx.us/index2.aspx?id=6148 Discovery Education- http://school.discoveryeducation.com/lessonplans/programs/lightning/