GEO 211 1st Edition Lecture 34 Outline of Last Lecture I Chapter 14 Thunderstorms tornadoes A Thunderstorms B Life cycle of ordinary storms 1 Cumulus stage 2 Mature stage intense storm 3 Dissipation stage updrafts begin to weaken and collapse C Types of thunderstorms 1 Single cell 2 Multicell clusters 3 Multicell lines squall line 4 Supercell D Severe thunderstorms produce one or more of these Outline of Current Lecture II Lightning and Thunder A Lightning can travel Within a cloud majority Cloud to cloud Cloud to air around it Cloud to ground B Lightning stroke C Electrification of clouds D Charge separation in the cloud E Cloud to ground lightning air between cloud base and ground is iodized first before lightning flashes F Approaching the ground the current of the positive charge starts moving up into the air return stroke though any conducting object Heat lightning These 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 Lecture II Lightning and Thunder A Lightning can travel Within a cloud majority Cloud to cloud Cloud to air around it Cloud to ground B Lightning stroke heats air to extreme temperature causing air to expand explosively creating a thunder C Electrification of clouds Involves ice pellets graupel hailstone in a cloud Hailstones freeze from outside in developing positively charged outer shell and a negatively charged interior As the interior freezes it expands Expansion causes outer hard shell to shatter into tiny charge fragments D 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 of the cloud As the cloud moves negatively charged cloud E 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 leader F 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 fires
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