13.1 Thunderstorms
-
Upload
migratorycoconut -
Category
Economy & Finance
-
view
1.077 -
download
4
description
Transcript of 13.1 Thunderstorms
13.1 Thunderstorms
Pages 328 - 333
Goal 1
Describe the 3 conditions required for thunderstorms to
form
Requirement # 1
Abundant moisture in the lower atmosphere
Image credit: steamy window by lyle58 on Flickr
Requirement # 2
Mechanism to lift moist air up for condensation to occur
Image credit: Arrow up the tree by net_efekt on Flickr
Requirement # 3
Unstable atmosphere
Image credit: May be Unstable by Ann Douglas on Flickr
Goal 2
Relate types of thunderstorms to their uplift mechanism
• Mountain thunderstorm– Uplift mechanism air mass convection
• May be assisted by orographic lift– Sunlit mountain surface warms air– Warm air rises to create thunderstorm– Usually occur in afternoon, after sufficient
warming
Image credit: “Storm clouds a’ Brewin” by Abu on Flickr
Mountain Thunderstorm
• Sea-Breeze thunderstorm– Uplift mechanism air mass convection– Sun warms land faster than water– Warm land air rises– Cool sea-breeze replaces warm air causing a
convection current– Rising air produces thunderstorms– Often occur in summer afternoons
Sea Breeze Thunderstorms
Image credit: NOAA, image is public domain (government)
• Frontal thunderstorm– Uplift mechanism air mass collision– Cold front advancement– Line of storm formation at frontal boundary– More common in summer months– Can occur at any time of day
Frontal Thunderstorms
Image credit: Beau Dodson, educational use permission can be seen at: http://www.weatherphotography.net/index.html
• Rare warm-front thunderstorm– These can occur if the warm air mass has a
high moisture content
Goal 3
Relate the 3 stages in the life cycle of thunderstorm to the
direction of air flow
• 1. Cumulus Stage– Updrafts of warm air rising– Moisture transported up– Condensation occurs– Latent heat relseased = more rising– Coalescence of raindrops
• 2. Maturation Stage– Updrafts and downdrafts occur equally– Cold air sinking– Rain falling– Warm air still rising– Windy
• 3. Dissipation Stage– Downdrafts of cool air falling– Storm loses energy, no more air rising– No new precipitation forming– Remaining rain falls from storm
Image credit: NOAA, image is public domain (government)