ERTH 2415 Lecture Notes - Lecture 1: Enhanced Fujita Scale, Cumulus Cloud, Fujita Scale
10 Oct 2016
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Warm: expands in less volume, rises, holds more humidity, molecules move more. Cold: contracts in volume, sinks, holds less humidity, molecules move less: in case you"re unsure this has already been mentioned in class so they"re good facts to know. Thunderstorm is a localized storm cloud that produces thunder and lightning, the individual cells develop over 20-30 minutes and as one cell dies another may develop near it. 3 stages of development: cumulus stage, mature stage, dissipating stage: cumulus stage: thunderstorm occurs when warm and moist air is lifted upward, there is no precipitation yet. Mechanical lifting- cold air undercuts warm air. Charges separate during the development of cumulus: positive at the top, negative at the base. In case you"re unsure remember that cumulus is a stage of development: when the positive and negative unbalance in regions becomes too strong lightning occurs. 2. stepped leader (negative charges move downward in intermittent steps) 3. connection (positive discharge leaps up from the ground)
