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Historical Data on Lightning and Tornado Deaths in the United States

This article provides historical data on lightning and tornado deaths in the United States from 1940-2011. It includes information on the factors contributing to the peak in tornado deaths in 2011 and the number of tornado deaths per million people since the late 1800s.

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Historical Data on Lightning and Tornado Deaths in the United States

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  1. http://www.washingtonpost.com/blogs/capital-weather-gang/ By Jason Samenow (Posted at 12:31 PM ET, 01/13/2012) Lightning deaths by year (1940-2011) and tornado deaths by year (1950-2011) (Data from National Weather Service) Tornado deaths per million people in United States since late 1800s (NOAA) Q: The peak in 2011 was due to a) Poor forecasting; b) lack of warning or education of public; c) simply too many and too strong tornadoes.

  2. Appendix A • Length: m • 1 km = 1000 m; • 1 m = 100 cm = 1000 mm = 106 micrometer (μm) • 1 inch (in.) = 2.54 cm • 1 foot (ft) = 12 in. = 12*2.54 = 30.48 cm = 0.3048 m • 1 mile (mi) = 1.61 km • 1 nautical mile = 1.15 mi = 1.85 km • 1 degree latitude = 111 km = 60 nautical miles • Q: 10 μm = ? a) 10-5 m; b) 10-6 m; c) 10-7 m

  3. (b) Area: m2 • 1 mi2 = 1.612 km2= 2.59 km2 • 1 ft2 = 0.32 m2= 0.09 m2 • Volume: m3 • 1 liter (l) = 1000 cm3 = 0.264 gallon (gal) US • (d) Mass: kg • 1 kg = 2.2 lb • So 20 mi/gal = 20*1.6 km/(1/0.26) l ~ 8 km/l • Q: where is the gas price higher? a) in the U.S. ($4/gal); • b) in China ($1.5/liter); c) same

  4. (e) Speed: m/s 1 km/hr = 1000m/3600s = 0.28 m/s 1 mi/hr = 1609m/3600s = 0.45 m/s 1 knot = 1 nautical mile/hr = 1850m/3600s = 0.51m/s (f) Force: newton (N) = kg m/s2 F = ma `a’ is acceleration (or change of speed with time) 1 dyne = 1 g cm/s2 =10-3 kg 10-2 m/s2 = 10-5 N earth’s gravity: g = 9.8 m/s2

  5. (g) Energy (heat, work): joule (J) = Nm • E = FL `L’ is distance • 1 J = 1 Nm = 0.24 Calorie (cal) • 1 cal = heat needed to raise temperature from 14.5oC • to 15.5oC of 1 cm3 of water • (h) Power: watt (W) = J/s • P = change of energy with time • 1 horse power (hp) = 746 W • Power of 10 • 10-9 10-6 10-3 10-2 102 103 106 1091012 1015 • Q: The work from lifting weight of 50 kg for 30 cm is • a) 1.5 J; b) 15 J; c) 150 J; d) 1500 J

  6. Pressure: pascal (Pa) = N/m2 • P = F/Area • 1 Pa = 1 N/m2 • 1 millibar (mb) = 100 Pa = 1 hecto Pa = 1 hPa • sea level surface pressure = 1013 mb • 1 mb ~ 10 m in depth • Q: what is the typical height of 850 mb above • sea level? a) 1.5 km; b) 2 km; c) 8.5 km

  7. 1 millimeter of mercury (mm Hg) = 1.33 mb because Hg density = 13,546 kg/m3; earth’s gravity = 9.8 m/s2; Over unit area (m2), 1 mm Hg mass = 10-3 * 13,546 = 13.5 kg F = mg = 13.5 *9.8 = 133 N P = F over unit area = 133 Pa = 1.33 mb Q: surface pressure 1013 mb = ? a) 500 mmHg; b) 760 mmHg; c) 1000 mmHg

  8. (k) Temperature: kelvin (K) K = oC + 273; oC = 5/9 (oF -32) oF = 9/5 oC + 32 (Table A.1 on p. 457 could also be used) Q: 104 oF = ? a) 20 oC; b) 30 oC; c) 40 oC Q: if temperature changes by 1 oC, how much does it change in oF? a) 5/9 oF; b) 1 oF; c) 1.8oF

  9. Chapter 2: Warming the Earth and the Atmosphere • Temperature and heat transfer • Balancing act - absorption, emission and equilibrium • Why the earth has seasons

  10. Temperature and Heat Transfer Air T is a measure of the average speed of the Molecules Warm less dense

  11. Temperature Scales • kinetic energy, temperature and heat K.E. = mv2, Internal energy = CvT, Heat = energy transfer by conduction, convection, and radiation • Kelvin scale: SI unit • Celsius scale: used in most countries • Fahrenheit scale: used for surface air T in U.S. • temperature conversions • Every temperature scale has two physically-meaningfulcharacteristics: a zero point and a degree interval. Q: A hot iron has lots of: a) energy; b) heat, while touching it will transfer heat to hand.

  12. Q: At the top of Mt. Everest, will the boiling point temperature • increase; • decrease; • not change?

  13. Latent Heat - The Hidden Warmth • phase changes and energy exchanges evaporation: faster molecules escape to air; slower molecules remain, leading to cooler water T and reduced water energy; lost energy carried away by (or stored in) water vapor molecule at boiling point temperature, molecules anywhere in the liquid could escape and vapor pressure equals the environmental pressure • sensible heat: we can feel and measure with a thermometer Q: Cloud formation [a) warms; b) cools; c) does not change the temperature of] the atmosphere? Q: Why is perspiration an effective way to cool your body?

  14. Stepped Art

  15. Conduction Conduction: heat transfer within a substance by molecule-to-molecule contact due to T difference good conductors: metals poor conductors: air For instance, touching a hot ground in summer in Tucson might burn your finger, but your finger is fine at 1 cm above surface. Q: Touching metal and wood in room T with your hand, which one do you feel cooler: a) metal; b) wood; c) equal

  16. Convection • Convection: heat transfer by mass movement of a fluid (such as water and air) • Thermals: rising bubbles of air that carry heat upward by convection • Soaring birds, like hawks and falcons, are highly skilled at finding thermals. • Convection (vertical) vs Advection (horizontal) Q: why does the rising air expands and cools?

  17. Radiation • Radiation: energy transfer between objects by electromagnetic waves (without the space between them being necessarily heated); packets of photons (particles) make up waves and groups of waves make up a beam of radiation; • electromagnetic waves In a vacuum, speed of light: 3*105 km/s • Wein’s law wavelength at maximum radiation: λmax = 2897 (μmK)/T • Stefan-Boltzmann law Radiative energy flux (Wm-2) : E = σT4 Q: In a vacuum, there is still: a) conduction only; b) convection only; c) radiation only; d) all of them? Q: Heat is transferred in a metal by: a) conduction only; b) convection only; c) both

  18. All things emit radiation • Higher T leads to shorter λ • Higher T leads to higher E • Shorter λ photon carries more energy • UV-C (.2-.29 μm) • ozone absorption • UV-B (.29-.32 μm) • sunburn/skin cancer • UV-A (.32-.4 μm) • tan, skin cancer • Most sunscreen • reduces UV-B only

  19. Radiation vertical scale differs much • electromagnetic spectrum • ultraviolet radiation (UV-A, B, C) • visible radiation (0.4-0.7 μm) shortwave (solar) radiation • infrared radiation longwave (terrestrial) radiation

  20. Q: I can see you, because: a) you emit visible light; b) you reflect visible light

  21. Selective Absorbers Atmospheric window: 8-12 μm The best greenhouse gas in the atmosphere is water vapor, followed by CO2 Atmospheric absorption of solar radiation is small Atmospheric absorption of infrared radiation is large

  22. In general, earth’s surface absorbs almost all infrared radiation. If all radiation is absorbed by an object, this object is called “blackbody” and earth’s surface is nearly a blackbody. Q: does a blackbody need a black color? a) yes, b) no Low-level clouds are also good absorbers of longwave radiation (and hence increase surface air temperature at night) Q: Why do high-level clouds not significantly increase surface air temperature at night? Q: does ozone strongly affects radiation (see previous two slides)? Answer: No. It absorbs UV below 0.3 μm (which contains small amount of solar radiation only). It also absorbs infrared radiation around 9.6 μm only. Q: Does ozone hole affect climate change? a) yes; b) no.

  23. Balancing Act - Absorption, Emission, and Equilibrium Without atmospheric green house gases (but with clouds), the earth average temperature is -18oC due to the balance of solar heating and longwave radiation loss With atmosphere, the earth surface temperature is 15oC due to the selective absorption of the atmosphere In other words, the 33oC difference is caused by the atmospheric green house effect. This statement in the book is incorrect!

  24. Zeng (2010; Eos Trans.) Without atmosphere (i.e., no greenhouse gases, no clouds, no aerosols), the earth average temperature is -5oC due to the balance of solar heating of half of the earth and longwave radiation loss from the earth surface With atmosphere, the earth surface temperature is 15oC due to the selective absorption of the atmosphere Therefore, the atmosphere effect refers to the 20oC difference (rather than 33oC)

  25. Enhancement of the Greenhouse Effect • global warming:due to increase of CO2, CH4, and other greenhouse gases; global average T increased by 0.6 oC in the past 100 yr; expected to increase by 2-6 oC at the end of 21st century • positive and negative feedbacks • Positive snow feedback: a) increasing temperatures lead tomelting of snow/ice; b) this decreases surface albedo and increases surface absorption of solar radiation; c) this increases temperature • Potentially negative cloud-temperature feedback Q: What is the water vapor-temperature feedback? Answer: 1) increasing air temperature; 2) increasing evaporation; 3) increasing water vapor in the air; 4) water vapor is an atmospheric greenhouse gas; 5) increasing air temperature; 6) positive feedback

  26. Warming the Air from Below • Radiation: heat the ground • Conduction: transport heat upward within 1 few cm of ground • Convection: transport heat upward within ~1 km of ground Only under special conditions, can air moves above ~1 km height and form clouds. Q: How high can air parcel move up in Tucson in summer afternoon in general? a) 1 km; b) 2 km; c) 4 km

  27. Incoming Solar Energy Light scattering:light deflected in all directions (forward, sideward,and backward), called diffuse light, by air molecules and aerosols. Q: Why is the sky blue? Answer: 1) because air molecules are much smaller than the wavelength of visible light, they are most effective scatterers of the shorter (blue) than the longer (red) wavelengths; 2) diffuse light is primarily blue Q: why is the sun perceived as white at noon? A: because all wavelengths of visible lights strike our eyes Q: Why is the sun red at sunset? A: 1) atmosphere is thick; 2) shorter wavelengths are scattered and only red light reaches our eyes

  28. Scattered and Reflected Light • Scattering:blue sky, white sun, and red sun • Reflection:more light is sent backwards • Albedo:ratio of reflected over incoming solar radiation fresh snow: 0.8 clouds: 0.6 desert: 0.3 grass: 0.2 forest: 0.15 water: 0.1 Surface absorption of solar radiation is simply (1 – albedo). Surface is a very good absorber of infrared radiation (~0.95) Snow is a very good absorber of infrared radiation, but it is a poor absorber of solar radiation.

  29. The Earth’s Annual Energy Balance Q: What happens to the solar energy at top of the earth’s atmosphere, in the atmosphere, and at surface? A: next slide Q: Most solar energy on average is: a) absorbed by surface; b) absorbed by atmosphere; c) reflected and scattered to the space Q: What is the energy balance at top of the atmosphere, in the atmosphere, and at surface? A: see slide Q: top: 100 (solar) = 30 (reflection) + 70 (longwave) surface: 51 (solar) = 7 (convection) + 23 (evap) + 21 (net longwave) air: 7 (conv) + 23 (evap)+ 19 (solar) = 49 (net longwave)

  30. Solar constant = 1367 W/m2

  31. Heat is transferred by both atmosphere and ocean Q: What is the fundamental driving force of wind patterns in the atmosphere? A: differential heating

  32. Why the Earth has Seasons Q: the earth’s season is caused by: a) tilt of the earth’s axis; b) earth-sun distance variation Q: the earth-sun distance is longer in: a) winter; (b) summer; c) equal • Q: if the earth’s axis were NOT tilted, would we still have seasons? • yes; b) no • Q: will sun set at 70oN on June 21? • a) yes; b) no

  33. Seasons in the Northern Hemisphere Factors determining surface heating by solar energy: 1) solar angle; 2) time length from sunrise to sunset. Q: why is Arizona warmer in summer than northern Alaska where sun shines for 24 hours (see figure)? A: sun angle is too low in Alaska so that 1) solar insolation (i.e., incoming solar radiation) per unit area is too small, and 2) atmospheric path for solar rays is much longer and most of the solar energy is scattered, reflected, or absorbed by the atmosphere

  34. While the astronomic winter starts on December 21, meteorological winter season is usually defined as DJF (Dec-Jan-Feb) based on the 3 coldest months Q: Why is temperature higher at 40oN on June 21 than on Dec 21? a) longer daytime; b) higher solar angle; c) both a) and b)

  35. Computing the maximum solar angle at noon on 21 June at latitude is simply: (90 +23.5 – latitude) Q: In Tucson summer, the sun rises from: a) northeast; b) nearly east; c) southeast Stepped Art

  36. Local Seasonal Variations • slope of hillsides: south-facing hills warmer & drier • vegetation differences Q: Without considering views, should Tucson homes have large windows facing a) south; b) north? Q: What would be the answer for a North Dakota home? a) south; b) north

  37. Q: why is the bridge in this figure the first to become icy?

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