GC 170 1st Edition Lecture 19 Outline of Last Lecture I Weather vs Climate II Drought a Definition b California c 1930 s Dustbowl d 1950 s Drought e Consequences f Wildfires i 2002 ii 2011 Outline of Current Lecture I Rainstorms Heavy or Intense events a Consequences b Tucson July 2006 c Colorado d Increased occurrence II Hurricanes a Hurricane Activity b Wind Shear c Concerns d Surge Storms Current Lecture I Average summer rainfall high variability from one year to the next a Not changing over time b Individual rainstorms that contribute to the total summer precipitation c Extreme storms that brings lots of precipitation in a short period of time i Consequences of heavy or extreme rainfall 1 Flooding 2 Crop damage 3 Increased water pollution ii Tucson July 2006 1 Persistent low pressure system brought moisture to southern AZ for four days 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 a Brought 10 12 inches of rainfall to southern Arizona II iii Colorado Sept 2013 1 17 inches of rainfall in four days 2 Annual amount of rainfall in 4 days 3 Extreme flooding throughout the Front Range Boulder Ft Collins iv Increased occurrence of extreme one day precipitation events over recent years 1 Warmer sea surface temperatures increases evaporation 2 Warmer atmosphere can hold more moisture 3 Clouds move over land and more rainfall occurs Hurricanes a Hurricane activity strength and duration increasing in recent decades with increasing sea surface temperatures i If sea surface temperatures become warmer hurricanes will become more intense ii Hurricane numbers have not increased over past century iii Difficult to predict especially if the upper troposphere also warms iv b Wind Shear i High wind shear large temperature gradient 1 Warm temperatures at the surface 2 Cool temperatures in the upper atmosphere a Intensifies a hurricane ii Low wind shear similar temperature throughout 1 Warm temperatures at the surface 2 Warm temperatures in the upper atmosphere a Causes a hurricane to weaken or break apart c Concern that hurricanes will get more intense and have higher rainfall amounts i Intensity relates to warmer sea surface temperatures leading to a stronger temperature gradient in the atmosphere ii Higher rainfall amounts will result from warmer sea surface temperatures leading to increased moisture in the atmosphere d Storm Surge i Water being pushed to shore by the storm winds 1 Sensitive to changes in storm intensity and direction 2 Can be more destructive when sea level is higher
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