weather and climate l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Weather and Climate PowerPoint Presentation
Download Presentation
Weather and Climate

Loading in 2 Seconds...

play fullscreen
1 / 79

Weather and Climate - PowerPoint PPT Presentation


  • 209 Views
  • Uploaded on

Weather and Climate Lecture 13: Severe Weather and Hurricanes Thunderstorms A thunderstorm is simply a storm containing lightning and thunder. Thunderstorms occur all over the world Formation - Ingredients Moisture (water vapor) in the lowest levels of the atmosphere

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Weather and Climate' - sandra_john


Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
weather and climate

Weather and Climate

Lecture 13:

Severe Weather and Hurricanes

thunderstorms
Thunderstorms
  • A thunderstorm is simply a storm containing lightning and thunder.
  • Thunderstorms occur all over the world
formation ingredients
Formation - Ingredients
  • Moisture (water vapor) in the lowest levels of the atmosphere
  • Cold, dry air aloft (2-3 miles above the surface)
  • Lifting mechanism
air mass single cell thunderstorms
Air Mass (Single-Cell) Thunderstorms
  • Formed by uneven heating of the earth’s surface
  • Brief, but well-defined lifespan with three stages
    • Cumulus Stage
    • Mature Stage
    • Dissipating Stage
mature thunderstorms
Mature Thunderstorms
  • The updraft can become so strong that it penetrates into a region of stable air, resulting in a overshooting top.
lifespan of a thunderstorm
Lifespan of a Thunderstorm
  • A single cell, consisting of an updraft and downdraft, lasts 20 minutes.
  • But we have all observed thunderstorms that appear to last longer than 20 minutes….

WHY?

multicell storms
Multicell Storms
  • Sometimes when the cold downdraft reaches the surface, it may force the warm, moist surface air upward
  • This rising air can condense and build a new thunderstorm

Multicell Cluster

Multicell Line (Squall Line)

straight line winds
Straight-Line Winds
  • Associated with a cluster of severe thunderstorms
  • May exceed 90 knots
  • If wind damage extends 250 miles along storm path, it is called a derecho.
tree damage
Tree Damage

What does it look like from a downburst vs. a derecho?

severe thunderstorm
Severe Thunderstorm
  • Hail ¾” or greater
  • Winds in excess of 50 knots (57.5 mph)
  • Tornado
capping inversion
Capping Inversion
  • An important component of creating a severe thunderstorm is the strength of the boundary layer cap.
    • Too strong nothing develops
    • Too weak numerous cumulus clouds
    • Just righthelps to funnel the air into a strong updraft
slide32

Tornado Wind Speed

As the tornado moves along a path, the circular tornado winds blowing opposite the path of movement will have less speed.

For example, if the storm rotational speed is 100 knots, and its path is 50 knots, it will have a maximum wind of 150 knots on its forward rotation side.

Figure 15.31

suction vortices
Suction Vortices
  • Many violent tornadoes contain small whirls inside them.
tornadoes vs mesocyclone
Tornadoes vs. Mesocyclone
  • Development of mesocyclone
  • Stretching – gives rotating air a faster spin
supercell
Supercell

View from East

tornadoes36
Tornadoes
  • Vertical Wind Shear (pencil example)
  • Horizontal roll meets updraft and is tilted vertically
slide37

Rotating Clouds as Tornado Signal

The first sign that a supercell may form a tornado is the sight of rotating clouds at the base of the storm, which may lower and form a wall cloud, shown in this picture.

Figure 15.41

lightning52
Lightning
  • The lightning we see is actually the return stroke, and comes from the ground.
slide57

Landspout Formation

Figure 15.43A

hurricanes tropical cyclones
Hurricanes (Tropical Cyclones)
  • Sustained wind speeds in excess of 74mph
  • Tropical origin
  • The clear area in the center is called the eye of the hurricane.
hurricanes
Hurricanes

Eyewall

hurricanes62
Hurricanes
  • The hurricane season runs from June to November. (sfc water is warm ~80oF)
  • Most Atlantic hurricanes form due to a wave coming off of Africa.
  • Hurricanes are very efficient storm systems
hurricane dammage
Hurricane Dammage
  • The high winds are not the most damaging part of hurricanes
  • Most damage is from waves, high seas, and flooding
  • About ¼ of hurricanes that hit the US coast will produce tornadoes
hurricane kenna october 2002
Hurricane Kenna October 2002

Picture @ Luis Rico Rojo

hurricane kenna october 200271
Hurricane Kenna October 2002

Picture @ Luis Rico Rojo

hurricane kenna october 200272
Hurricane Kenna October 2002

Picture @ Luis Rico Rojo

hurricane kenna october 200273
Hurricane Kenna October 2002

Picture @ Luis Rico Rojo

hurricane kenna october 200274
Hurricane Kenna October 2002

Pictures @ Luis Rico Rojo

hurricane kenna october 200275
Hurricane Kenna October 2002

Picture @ Luis Rico Rojo

naming hurricanes
Naming Hurricanes
  • 1953-1977 female names were used
  • 1978 to current alternates male/female names
  • A name can be retired if a hurricane is category 3 or higher, with lots of damage
floods and droughts
Floods and Droughts
  • Large widespread floods, like the Mississippi River, occur when the weather pattern becomes locked in.
  • Similarly droughts occur when a weather pattern becomes locked in. (i.e. domination by high pressure)