PHY 118 final study guide -chapter 10 (1)

PHY 118 final study guide -chapter 10 (1) - PHY 118 Final...

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PHY 118 Final Study Guide: Chapter 10 (1) I. Thunderstorms: Storm that generates lightning and thunder a. Characterized by strong up and down circulations with variable and gusty winds b. Dynamic Instability occurs during the development of a T-storm i. Form when warm, humid air rises in an unstable atmosphere c. Produces gusty winds, heavy rain, and hail d. May be produced by a single cumulonimbus cloud or by a aggregate of them, and will affect a small or large area respectively e. Frequently produced on the cold front of a mid-latitude cyclone f. Unequal heating of surface and diverging winds aloft II. Air-Mass Thunderstorm: a. Frequently occur in mT air moving northward from the Gulf of Mexico i. Warm, humid air masses contain most moisture in lower levels and become unstable when heated from below or lifted along a front b. Spring and Summer c. Mid-afternoon, surface temperatures are highest and promote unstable atmosphere d. Mountainous regions e. Occur as part of the general convergence and frontal wedging that accompany the mid-latitude cyclones in the eastern u.s. f. Occur in association with convergence along the ITCZ, but are not severe g. Unequal heating of surface aids growth > form as scattered, isolated cells h. 20% of moisture that condenses in it actually leaves the cloud as precipitation i. Stages of Development i. Cumulus Stage – 1. Uneven heating of surface creates strong updrafts that act to build the storm and produce “fair weather” cumulus clouds 2. Cumulus clouds evaporate within minutes a. Important because it moves moisture aloft and makes air sufficiently humid to produce new clouds that grow vertically 3. Release of latent heat through evaporation allows warm air to rise higher and higher 4. Extending past the freezing level, the cloud begins the Bergeron process and produces precipitation 5. Precipitation creates drag that is too great for the updrafts to continue; initiates a downdraft further aided by the inflow of cold, dry air surrounding the cloud ( Entrainment) 6. Intensifies downdraft because: a. The new cold air is heavier and drier than previous air b. Causes falling precipitation to evaporate (cool) and cools the air within the downdraft ii. Mature Stage – (most active period of t-storm) a. As downdraft leaves cloud, precipitation is released b. Downdrafts diverge at surface and are felt before precipitation occurs c. Updrafts exist alongside downdrafts and continue to enlarge cloud
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d. Once cloud reaches top of unstable region, updrafts diverge and create the
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This note was uploaded on 05/05/2011 for the course PHY 118 taught by Professor Schroeder during the Spring '11 term at Miami University.

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PHY 118 final study guide -chapter 10 (1) - PHY 118 Final...

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