Eos 170 Climate And Weather (Thunderstorms, Tornadoes)

Front 1

Are weather and climate different?

Back 1

yes

Front 2

what is weather?

Back 2

meteorological conditions including temperature and precipitation and wind that exist at a time and place

Front 3

what is climate?

Back 3

meteorological conditions including temperature and precipitation and wind that prevail in a particular region

Front 4

weather changes on short and long term scales due to: (4)

Back 4

> meteorological conditions
> daily heating/cooling
> seasonal variations
> climate changes

Front 5

Climate changes due to natural causes on a long or short time scale?

Back 5

Longer time scale (decades to millions of years)

Front 6

What are the natural causes of climate change?

Back 6

Plate tectonic motion
Variations in earth's orbital properties (milankovitch cycles)

Front 7

What is orbital eccentricity?

Back 7

change in orbital shape (100,000 yr cycle)

- it is more elliptic --> farther from the sun, less solar heating coincides with broad glacial cycles over past million years

Front 8

What is orbital tilt?

Back 8

changes in inclination of earth's spin axis (41,000 year cycle)
- greater tilt --> greater seasonal extremes: colder winters, less snow; warmer summers, increased melt. Result: decreased glaciation, warmer temperatures

Front 9

What is orbital wobble?

Back 9

changes in spin axis direction (same tilt)
- "Procession of equinoxes" 19-23k year cycle
- presently earth closest to sun during northern winters --> milder winters and summers in north than in south

Front 10

How does the Greenhouse effect change climate?

Back 10

> solar radiation with short wavelengths (visible light) heats land and oceans (about 50% absorbed)
> heated objects radiate energy at long wavelengths (infrared, radiation)
> greenhouse gases in the atmosphere absorb outgoing infrared radiation as heat, preventing loss to space

Front 11

What are the anthropogenic causes of greenhouse gases?

Back 11

- CO2 from burning fossil fuels and forests
- CH4 produced by vegetation decomposition in absence of O2
- N2O produced from chem. fertilizers and auto combustion

- O3 from automotive/industrial gases

- CFCs from coolents and solvents

Front 12

What are some predictions of climate change?

Back 12

- uneven increase in temp.
- more severe extreme weather events

- more frequent extreme weather events

Front 13

What are droughts usually caused by?

Back 13

entrenched high pressure ridge
> descending warm dry air desiccates land
> higher pressure ridge blocks inflow of moist air

Front 14

Are droughts expected to increase in severity + frequency due to climate change or decrease in severity + frequency?

Back 14

Increase

Front 15

Have heat wave related deaths been increasing in Canada?

Back 15

No - decreasing. Virtually no deaths anymore.

Front 16

When was the most recent very bad Canada wide heat wave? Did people die?

Back 16

1936 - 1180 Canadians died

Front 17

How many people died in the European heat wave (the worst in past 150 years)

Back 17

35,000 people died

Front 18

Are heat waves predicted to get worse due to climate change?

Back 18

yes - more frequent and severe heat waves

Front 19

(5) ways thunderstorms can kill?

Back 19

> lightning
> fires
> hail
> wind
> flash floods and rains

Front 20

3 stages of thunderstorm formation:

Back 20

1. early stage: rising warm, moist air
2. mature stage: warm updrafts and cool downdrafts

3. dissipating stage: downdraft dominate. cloud evaporates

Front 21

What height is the condensation level at?

Back 21

6 kms

Front 22

describe the early stage of thunderstorm formation:

Back 22

warm moist air heated near ground surfaces rises, passes through condensation level
> water vapor condenses to liquid droplets, forms cloud column
> condensation releases latent heat of vaporization further uplifting air mass

Front 23

describe the mature stage of thunderstorm formation:

Back 23

droplets and/or ice crystals become heavy enough to precipitate causing cold downdrafts
> updrafts and downdrafts operate side by side
> causes gusty winds, rain, hail, lightning

Front 24

describe the dissipating stage of thunderstorm formation:

Back 24

Downdrafts drag in surrounding cool dry air overwhelm warm updrafts
> thunderclouds evaporate into surrounding air

Front 25

How often does lightning strike worldwide per second?

Back 25

100 strikes per second/9 million strikes per day

Front 26

T/F; lightning on a year to year basis causes more deaths in Canada/USA than any other natural hazard?

Back 26

true

Front 27

What causes lightning?

Back 27

electrical charge seperation in thunderclouds due to updraft/downdraft collisions between super-cooled water droplets and ice crystals
> collisions transfer slight positive charge to ice crystals, slight negative charge to water-ice mixture
> updrafts drive lighter ice crystals up causing positive charge accumulation at cloud top
> gravity pulls heavier graupel down, causing negative charge accumulation at cloud bottom
> cloud charge accumulations induce opposite charge accumulation in ground

Front 28

lightning strike is electrical discharge between opposite charge accumulations between what (3)?

Back 28

- between clouds and ground
- between clouds

- within clouds

Front 29

What produces the sound of thunder?

Back 29

rapid thermal expansion of air (caused by lightning's fast speeds >10,000km/h, and high temps. 30,000'C)

Front 30

does hail form during thunderstorms?

Back 30

yes

Front 31

does hailstorm distribution differ between thunderstorms?

Back 31

yes, cold air distribution is needed/variable

Front 32

how fast can tornadoes be?

Back 32

up to 500km/h

Front 33

T/F; the most tornadoes in the world exist in Europe?

Back 33

false: the most exist in USA, Canada second, then Europe

Front 34

What is the Fujita Scale?

Back 34

6-level scale for classifying tornadoes according to:
> storm damage
> wind speed

Front 35

On the Fujita Scale, what is the most damaging class?

Back 35

F5 - incredible damage

Front 36

How do tornadoes form in North America?

Back 36

>low altitude North flow of warm moist air from Gulf of Mexico
> mid-altitude winds of south east of cool-dry air from Canada or Rockies
> high-altitude, high jet stream winds to East from Appalachian mtn range area
- the 3 air masses moving different directions cause rotation within thunderstorm clouds

Front 37

Where is "Tornado Alley"?

Back 37

USA Great Plains between Rockies and Appalachians

Front 38

Do all thunderstorms form tornadoes?

Back 38

no

Front 39

what is required of a thunderstorm to create a tornado? (2 types)

Back 39

> single-cell thunderstorm: moisture condenses from rising hot moist air falls through thundercloud causing cool downdraft that suppresses updraft, reduces intensity of thunderstorm and chance of tornado
> super-cell thunderstorm: wind shear tilts thundercloud into anvil shape, separating warm updraft and cool downdraft allowing more intense thunderstorm and higher chance of tornado