GEO 211 1st Edition Lecture 34 Outline of Last Lecture I. Chapter 14- Thunderstorms/tornadoesA. ThunderstormsB. Life cycle of ordinary storms:1. Cumulus stage2. Mature stage: intense storm3. Dissipation stage- updrafts begin to weaken and collapseC. Types of thunderstorms1. Single cell2. Multicell clusters3. Multicell lines (squall line)4. SupercellD. Severe thunderstorms produce one or more of these:Outline of Current Lecture II. Lightning and ThunderA. Lightning can travel:- Within a cloud (majority)- Cloud to cloud- Cloud to air around it- Cloud to groundB. Lightning strokeC. Electrification of cloudsD. Charge separation in the cloudE. Cloud to ground lightning- air between cloud base and ground is iodized first before lightning flashesF. Approaching the ground, the current of the positive charge starts moving up into the air (return stroke) though any conducting object- Heat lightningThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Current LectureII. Lightning and ThunderA. Lightning can travel:- Within a cloud (majority)- Cloud to cloud- Cloud to air around it- Cloud to groundB. Lightning stroke- heats air to extreme, temperature causing air to expand explosively, creating a thunderC. Electrification of clouds- Involves ice pellets (graupel/hailstone) in a cloud- Hailstones freeze from outside in, developing positively charged outer shell and anegatively charged interior- As the interior freezes, it expands- Expansion causes outer hard shell to shatter into tiny charge fragmentsD. Charge separation in the cloud- Positively charged fragments are tossed to upper reaches of cloud called updrafts- Dense (negative) charged interior of (super cooled water) remain at lower part ofthe cloud- As the cloud moves negatively charged cloudE. Cloud to ground lightning- air between cloud base and ground is iodized first before lightning flashes- Cloud base frees electrons creating a narrow conductive path called a leader- Leader elongates in a series of steps called step-leader or stepped leaderF. Approaching the ground, the current of the positive charge starts moving up into the air (return stroke) though any conducting object- When they meet, a luminous flash is observed- Return stoke complete, negative charge from cloud base is carried down- Dart leader re-ionizes the conductive path from the cloud- Heat lightning- distant lightning from thunderstorms that’s seen but not heard- A lightning flash, followed by a thunder 5 seconds later, occurred about a mile away- Dry lightning occurs in storms that produce no rainfall an start forest
View Full Document
Unlocking...