GC 170 1st Edition Lecture 19Outline of Last Lecture I. Weather vs ClimateII. Droughta. Definitionb. Californiac. 1930’s Dustbowld. 1950’s Droughte. Consequencesf. Wildfiresi. 2002ii. 2011Outline of Current Lecture I. Rainstorms (Heavy or Intense events)a. Consequencesb. Tucson July 2006c. Coloradod. Increased occurrenceII. Hurricanesa. Hurricane Activityb. Wind Shearc. Concernsd. Surge StormsCurrent LectureI. Average summer rainfall: high variability from one year to the nexta. Not changing over time b. Individual rainstorms that contribute to the total summer precipitationc. Extreme storms that brings lots of precipitation in a short period of timei. Consequences of heavy or extreme rainfall1. Flooding 2. Crop damage 3. Increased water pollutionii. Tucson July 20061. Persistent low-pressure system brought moisture to southern AZ for four daysThese 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 Arizonaiii. 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 years1. Warmer sea surface temperatures increases evaporation 2. Warmer atmosphere can hold more moisture 3. Clouds move over land and more rainfall occursII. Hurricanesa. Hurricane activity (strength and duration): increasing in recent decades with increasing sea surface temperaturesi. If sea surface temperatures become warmer, hurricanes will become more intenseii. Hurricane numbers have not increased over past century iii. Difficult to predict, especially if the upper troposphere also warmsiv.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 apartc. Concern that hurricanes will get more intense and have higher rainfall amountsi. Intensity relates to warmer sea surface temperatures leading to a stronger temperature gradient in the atmosphereii. Higher rainfall amounts will result from warmer sea surface temperaturesleading to increased moisture in the atmosphered. Storm Surgei. 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
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