final exam w&s

Flood probabilities for any single year--For example, what is meant by a 100 year flood?

  • 1 in 100 chance for that flood to happen every year. 

The role of urban sprawl in estimating the likelihood and magnitude of future floods

  • When people move into a city they have to build more homes. When there is flooding the ground isn’t able to absorb the water because there are too many buildings in the way. 

Characteristics of flash, widespread, and coastal floods

  • Flash flood: little no warning, rapid, mostly on small rivers and streams, related fatalities are a result of floods

  • Widespread: large amount of rainfall over days, last a week or more, greater economic losses 

  • Coastal: can occur as a result from tsunamis, rise in ocean due to storm surge during a strong storm

watershed , stage, floodstage

  • Watershed: drains into a river or stream

  • Stage: height of the water surface of a river

  • Floodstage: when the river rises big enough to damage a property

Floodplains

  • Land that has been repeatedly flooded

Levees

  • An embankment that prevents the flow of water onto a floodplain

Weather patterns that relate to flooding--what are they and what are some of their major characteristics?  (Landfall of Tropical Cyclones, Frontal Overrunning, Atmospheric Rivers)

  • Tropical cyclone: provides extreme amount of rainfall

  • Frontal overrunning: precipitation is north of weather front, the front does not move very much because it is stationary

  • Squall lines: line of thunderstorms that are border along the front

  • Pineapple express (also known as atmospheric rivers): source of moisture is near hawaii which is carried to california, flows like a river in the air

Flash flood watches and warnings

  • Watch: announcement describing the flood is possible

  • Warnings: announcement that the flood has already occured

Coastal Flood Warnings

  • Strong onshore winds high tides within 12 hours

Thunderstorms--what are they and when are the worst threats?

  • When are thunderstorms the worst threats: april-june

  • What are thunderstorms: occur in the atmosphere and are essential for agriculture and water sources

3 stages of an ordinary thunderstorm

  • First: cumulus stage: updrafts and warm moist air

  • Second: mature stage: peak stage, thunder and lightning, air is rising and sinking

  • Third: dissipating stage: downdrafts and rain begin to spread throughout the air, cutting energy and moisture off

Characteristics of a severe thunderstorm

  • Contains one or more of the following: hail with a 1-inch diameter or larger, wind speed of 58 mph or greater, tornadoes

4 elements that are necessary for the development of a severe thunderstorm

  • 1: source of moisture

  • 2: unstable atmosphere 

  • 3: mechanism to trigger updrafts ( just have to have a way of getting the air to move upwards)

  • 4: vertical windshear ( reversal in wind direction )

Mesoscale convective systems

  • Mesoscale: scale of meteorology going from a small storm to multiples storms, difficult to detect on radar imagery because the difference in temperature between the air masses is so small


Supercell Thunderstorms

  • Large rotating single cell thunderstorm. Can cause heavy strong winds, hail, tornadoes etc. bad things in a thunderstorm

What do we know about the relationships between thunderstorms and global climate change?

  • Length of winter will reduce, early spring means early thunderstorm season, weakened jet stream means less supercell storms

Where does the greatest density of lightning flash occur?  Why?

  • Along central florida and south atlantic coast 

Definition of lightning and major characteristics--length, diameter, and temperature

  • Southeast is most common in US for lightning bc of humidity, easier for electrons to move creating lightning, 3 miles long, 1 inch diameters, 54,000 fahrenheit 

Protons, Electrons, Charges, Currents

  • Protons: positively charged particles

  • Electrons: negatively charged particles 

  • Charges & Currents:  electrons make up majority of the currents because they move easily

Conductors vs. Insulators

  • Conductors: materials that allow electric charge to flow through them easily (metal and water)

  • Insulators: electric currents cannot pass through this material

Major stages of a lightning stroke (definitions, step-by-step)

  1. Stepped leader: develops because electrons want to take the path of least resistance downwards, multiple “streams” or channels of electrons coming to give a forked appearance. 

  2. Return stroke: positive stream will meet the negative down flowing current creating a powerful return stroke. Important because the flash of lightning develops. 

  3. Dart leader: ionized path or channel that allows another large stream of electrons to move down. 

  4. 2nd return stroke: ensures that current can enable the lightning flash to move across the ionized channel.  

Heat Lightning 

  • Is caused by a thunderstorm that is distanced away also is the remnants of a thunderstorm. 

What causes the sound of thunder?

  • The sound waves that are generated by thunder are able to bend and bounce off buildings, hills, and scattered through the air. 

Tips for staying safe during lightning

  • Go inside and stay away from electrical appliances, don’t take a shower or be in contact with indoor water supplies, if outside: do not go under a tree, don’t lay on the ground, crouch down as close to the group as possible and minimize ground contact by staying on your toes or heels. A car with a metal frame is safe to be around as well. 

2 major ideas from 2 presentations: 

Hurricane sandy: 

  • 30-40 feet of beach erosion happened & only new york got money for damages but 24 states were hit

Tornado Xenia: 

  • The only people alerted about this was schools and the weather channel & ohio is now the leading state with communication stations