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Microbursts occurred right outside our classroom during class last Wednesday. Wind gusts reached 70 mph (hurricane force starts at 76mph).

Microburst is typically very sharp, gusty and brief down-draft of air.

Usually associated with thunderstorms (what goes up must come down).

This one, however, was caused by brief rain (dry front) that evaporated on the way down (virga). Evaporation cooling caused air to become more heavy and thereby descend even faster.

Weather radar (Doppler) failed to detect the microburst activity because the descending air did not contain enough water droplets to reflect the radar signal back to the receiver.

Wildfires: Colorado, Utah, California, are more likely during dry months. Fires are more vigorous when air is relatively more humid (daytime and dry weather).

www.telegraph.co.uk

Neola Wildfire – 2007Katie

Source: www.telegraph.co.uk

U.S. Weather-Related Deaths (1988-2007 - textbook, page 6)

- Tornadoes – 54- Hurricanes – 66- Lightning – 53- floods – 81(rip currents = 200 dead)

Utah Climograph

Utah Climograph

Rainy season is cooler as well as more humid

Dry season feeds and rewards fires

Santa Ana winds feed wildfires

www.rain.org

MeteorologyAtmosphere and Sky

Lithosphere (geosphere – rocks)HydrosphereAtmosphere

Biosphere

Our subject is the atmosphere, but hydro “water” is a KEY element in the atmosphere.

Meteorology Atmosphere and Sky

WindPressure

TemperatureCloudiness (condensation)

HumidityPrecipitation

Outlook -- generalized climate-based view of history, like “Poor Richard’s Almanac”

Forecast – general outlook – trends, spoken as probability or ranges of time and place

(statistics or chances – percentages)

Prediction – is more about date, time, place and magnitude of the event (the Earth will end midnight on December 21, 2012)

Planning-- Learning from the past, anticipating hazards and preparing for them (WFRC emergency prep plan, and annual “Shake Out” events)

Scientific Inquiry• Observation• Recognition of patterns• Hunch about the future• More focused observation & better tools• Hypothesis testing – a proposal that we test by

experiment. We use statistical tests to ask:

“What are the chances that this is just a coincidence?”

• We use test results to organize more observation.• Eventually we adopt a working theory (very little in this world reaches the level of

law, proof or axiom)

• For some, we create paradigms -- reliable conclusions that we use for operations: design, construction, investment.

Theories are powerful

A “paradigm” is a theory with special status because of its power to explain things.

Much of what we do in this world is not based on proofs, but only paradigm theories that just keep working for us, even though we may never

get to see what’s really inside.

Observations

- Ground instruments- Ground to sky- Balloons – with radiosondes- Airplanes- Non-orbit rockets- Satellites

Trends

Weather and climate are always changing – data for recent decades suggest yet another warming trend -- more warmth, more dryness – more drought.

World average annual temperatures started rising behavior humans played a significant role.

With the industrial age, our likely effect now is that we are adding further warmth, mostly by burning fossil fuels.

Earth Circle

SphereSpheroid

Oblate SpheroidLumpy, Oblate Spheroid

Earth- atmosphere is only 100 miles thick

- dry crust is only 5 to 50 miles thick (molten below)- both are moving convectively

Tectonic Forces and Terrestrial Heat

Solar energy and Earth internal energy are both produced by radioactivity – decay of heavy, unstable atoms into stable atoms: uranium gradually turns into lead.

Heat from radioactive earth produces convective flow, like a simmering pot on the stove. The same is true of the atmosphere - convective circulation.

Plane of Ecliptic

Seasonal Change

Source: www.astronomy.org

Source: commons.wikimedia.org – Earth-lighting-summer-solstice EN.png

Earth Dimensions

• Diameter = D – distance through the middle• Circumference = C – distance around the circle• Pi = π = a standard, fixed, constant relationship

between C and D

D = 7,923 miles -- about 8,000 milesC = 24,900 miles -- about 24,000 miles π = 3.1415868. . . -- about 3.0

So . . . .

C = π x D 24 = 3 x 8D = C / π 8 = 24/3π = C / D 3 = 24/8

24 hours in a day – 24 time zones360 degrees in a circle – 15 degrees per time zone. The Earth turns 15 degrees per hour.At the equator, each time zone spans 1,000 miles.

Earth curves down at three feet per mile

Source: Wikipedia.org/wiki/Figure_of_the_Earth

Earth coordinatesLatitude & Longitude

Source: worldwind.arc.nasa.gov

Geographic Coordinates

Latitude (like a ladder) – lines going east-west that measure north/southLongitude (long lines) that go from pole to pole, measuring distances or time east/west.

Euclidean or flat cartesian grid applied to a sphere: - lines of latitude vary in length;- lines of longitude are curved;

a compromise.

World Time Zones

World average annual temperature: 59°F

Lima, Ohio, annual average temperature: 59°F

Lima, Peru, annual average temperature: 59°F

Climate is the sum of all weather across time. Climate cannot predict the weather.

Climograph

Source: shannonmapcatalog.blogspot.com

Source: aronhotalen.blogspot.com

Weather Variability

Without atmosphere:- Earth temperature would be +5° degrees F,

instead of 59 °F;- Temperature would vary by hundreds of

degrees, rather than by just tens of degrees:.

Contents of the Atmosphere

N2 = 79%

O2 = 21%

O3 = ozone

Ch4 = methane

CO = carbon monoxideCO2 = carbon monoxide (rising from 280 pm to about 400 ppm

PM = particulate matter (PM2.5, PM10)

H2O = water vapor (1-4 percent by volume)

Oxides of Nitrogen and Sulfur (and others)

Permanent gases

Variable gasesCh4

Atomic WeightsHydrogen = 1Carbon = 12Nitrogen = 14Oxygen = 16Sulfur = 32

So . . . . What are the weights of atmospheric molecules?O3 = ozone

Ch4 = methane (much more powerful GHG than carbon dioxide)

CO = carbon monoxide (poison)

CO2 = carbon monoxide (rising from 280 pm to about 400 ppm

PM = particulate matter (PM2.5, PM10)

H2O = water vapor

Source: Globalwarmingweb.comN2O

Solar heating is indirect, by absorption, conversion and re-

radiation

Atmospheric gases are mostly transparent to solar photons (short

amplitude) except for . . . . . ?

Review the “Ozone” story

Atmospheric ozone (made naturally by interaction of oxygen with in-coming solar Uv (ultraviolet) solar energy.

Ground-level ozone created by lightning, ocean waves and a host of human processes (cars and industrial activity).

Chlorofluorocarbons and other man-made chemicals break down ozone, preventing ozone from blocking Uv.

Ground-Level Ozone and Smog

Anthropogenic oxides of nitrogen and sulfur (industry and automobiles) interact with sunlight to produce more ground-level ozone.

Atmospheric carbon dioxide seasonal adjustment and gradual base increase

Most land mass is in the northern hemisphere, so most plant growth and CO2 absorption during March to

October.

Atmospheric warmth budget

Of every 100 photons of solar energy received:- 31 are reflected back into space (no effect)- 69 are absorbed, converting to thermal energy

(heat):- 45 go into earth and water- 24 go into the atmosphere (3 alone go into ozone layer)

More than 99.9 are re-radiated back into outer space. Global warming (?) and HC storage are exceptions.

Energy Transfer

Radiation from outer space travels across empty space. The portion that is not reflected back out is absorbed, converting to thermal (infrared), energy transfers by:- Convection- Conduction- Re-radiationMostly short wave radiation IN, mostly long wave radiation going back OUT. (automobile windshield example)

British Thermal Unit - Btu

Energy needed to raise the temperature of one gram of water 1 degree F.

Role of Dust and Clouds is Mixed

- Aerosols and condensation (opacity) reflect incoming radiation (mostly short wave).

- They also help keep longer wave radiation from escaping back to space.

- So, solids and visible liquids in the atmosphere act as a ‘blanket’, keeping energy out, and keeping it in.

- Cloudy weather will be cooler during the day and warmer at night with the ‘blanket’ effect.

- The same effect results from being downwind from a large water body.

Allred’s Three Climate RulesLand mass heats and cools more quickly than water

Distance from:- Large water body- Sea level- Equator- Downwind?

- Annual and daily temperature range for Singapore and Buffalo, NY (east side of northern continent) and Tooele.

Thermal Structure of the Atmosphere

Troposphere – lowest region, a mixing zone (6 miles)Where storminess and surface heating occur – convection and circulation, aerosols and water vapor. Temperature generally drops with altitude.Stratosphere – ‘layered’ region, including the ozone layer. Rising temperature with altitude due to ozone (30 miles).Mesosphere - cooling with height, very thin air, virtually no air pressure, includes the coldest part of the atmosphere (50 miles).Thermosphere – virtually no air, but extreme heating of solid objects, caused by being first line of contact with incoming radiation.

General Environmental Lapse Rate

Most atmospheric heating occurs near absorbing surfaces (water, dirt and thicker atmospheric layers near the surface of the Earth)Air temperature generally declines by 3-5°F per 1,000 feet of increasing altitude. Use 3.0°F for extreme wet air and 5.0°F for extreme dry air.

Electromagnetic Spectrum

Higher energy levelLower energy level

Anecdotes

- Holes in the ‘window’ of a microwave oven- B-52 radar and flash bulbs- U-Boat “Biscay Cross” – centimetric radar- Cell phones through glass & a steel elevator

800 MHz, 1900 MHz, 2.4 GHz (2,400 Mhz)

- Uv and X-ray amplitudes fit skin cell structure- Earth is not heated directly by the sun, by

indirectly by water, soil and air by conversation to IR band after absorption.

Solar Angle of Incidence

Most solar energy is received near the equator.

Feedback(textbook, page 17)

- Positive ‘loop’ reinforces the previous event or pattern, leading to more of the same. Tends to result in instability, or eccentricity.

- Negative ‘loop’ promotes stability by reacting to reduce the factors that caused the previous event or trend.

- Example: world-wide melting of surface ice reveals darker, more energy-retaining surfaces underneath, promoting more heat retention.

Hydrologic Cycle

Source: wikimedia.org

Six time more water is carried by wind over North America than by its rivers.

Carbon CycleHydrocarbon production – store solar energy – plant growth

H2O + CO2 = + => HC + O2

Release stored solar energy by combustion:

HC + O2 => H2O + CO2 + heat

Combustion does also release some CO and PM and Nox compounds. If HC (fuel contains sulfur) then sulfur compounds. Mostly, burning non-fossil fuels is just recycling carbon.

At low temperature combustion, such as chemical combustion by animals, nitrogen and sulfur compounds are not ‘oxided’ into air pollution. Animals do produce methane, a powerful greenhouse gas.

Air Pressure Declines with Altitude

Unlike solids and liquids, gases can expand or contract to fill any space.Atmospheric gases are compressed near the surface due to gravity.Air pressure at sea level is about 14.7 pounds per square inch, or 29.92mb.At 18,000 feet altitude (3.5 miles above sea level), air pressure has declined by half (½).

In Troposphere, temperature declines with altitude except for

brief weather variations that include storms, fronts and inversions

General environmental lapse rate for:dry air = 3.0 degrees/1,000 feetwet air = 5.0 degrees/1,000 feet

Russell’s ePort

Coldest Air in Lower 48 States

Big Piney, Montana -- 70 degrees F below zeroPeter’s Sink, Utah -- 69.5 below zero

Routinely, places like Thief River Falls, Minnesota and Houlton, Maine record daily typical coldest winter temperatures in the lower 48 states.

- Land heats and cools more quickly than water.- Change in temperature means change in

pressure (higher temp, more vigorous molecule movement).

- Change in pressure means change in wind.- Wind brings change in humidity, and helps

evaporate water to produce more or less humidity.

- Water vapor (evaporated water) means stored energy, easily transported by wind.

Three States of Water

Vapor – high energy storage (lose heat to change state)Liquid – moderate energy storageSolid (ice) – lower energy storage (add heat to change)

Even at 100 F degrees below zero, water contains large amounts of energy – absolute zero is more than 400 F degrees below zero.

So, blizzards and ice storms are still highly energetic storms, by containing large amounts of heat (relatively speaking).

Anecdote- citrus farmers in Florida

Humidity Relative and Absolute

Vaporized water in the atmosphere varies from 0.2 to 4.0 percent by volume.Air capacity for humidity varies mostly by air temperature, but also by air pressure, aerosols (PM) and small factorsFor precipitation to occur, condensation nuclei are needed (aerosols or ice)

Calculate Relative Humidity

Water’s Affinity for Heat

- Specific heat capacity - Opacity – clarity – depth of water body- Convective circulation – vertically &

horizontally- Conductive circulation- Re-radiation

Water and Human Comfort

- High humidity makes you feel worse when it’s cold and when its hot.

- Dry weather feels closer to the actual temperature.

Water also transfers heat by convection

Gulf Stream (and others) carry warm surface water from the Tropics north and south toward the poles.

Polar return flow down deep and surface ice bergs move cold water toward the Equator.

If the Tropics (equatorial) receive much more solar energy – angle

plus duration . . . .

– then why is Arizona hotter than the Tropics during summer?

Because Arizona does not have enough water available to create humidity, condensation or . . . .

cloud cover (for reflecting solar radiation back

into space)

Paving and dark surfaces and relatively less shade and green plants mean that heat is absorbed and radiated back into the air rather than reflected or converted to hydrocarbons (plant growth).

Urban Effect on the Globe?

If cities are getting bigger and hotter, then could apparent ‘global warming’ be explained by the fact that country weather stations are now surrounded by asphalt and other “heat island” elements?

Wind Chill and Heat Stress Indexpages 89 and 108

Wind chill - Skin has a boundary layer of warm, humid air that is removed by wind, resulting in

‘wicking’ heat away from the body, making cold more penetrative.

Heat Stress is amplified by high humidity:

1. Humid air contains more latent, or hidden heat

2. Humid air is less able to absorb perspiration by evaporation, thus less cooling by evaporation

UV Index

0-2 Low > 60 minutes to burn3-5 Moderate 40-60 minutes6-7 High 25-40 minutes8-10 Very High 10-15 minutes11-15 Extreme < 10 minutes to burn

SPF – sun protection factor ( for sun screen)

Evaporative cooling vs

Compression cooling

Heating Degree Days (HDD) vs Cooling Degree Days (CDD)

page 87