Transcript Meteorology – Atmosphere and Sky

Local News
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 – 2007
Katie
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
Meteorology
Atmosphere and Sky
Lithosphere (geosphere – rocks)
Hydrosphere
Atmosphere
Biosphere
Our subject is the atmosphere, but hydro “water” is a KEY element in the atmosphere.
Meteorology
Atmosphere and Sky
Wind
Pressure
Temperature
Cloudiness (condensation)
Humidity
Precipitation
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)
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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
Sphere
Spheroid
Oblate Spheroid
Lumpy, 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 – Earthlighting-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 miles
C = 24,900 miles -- about 24,000 miles
π = 3.1415868. . . -- about 3.0
So . . . .
C=πxD
D=C/π
π=C/D
24 = 3 x 8
8 = 24/3
3 = 24/8
24 hours in a day – 24 time zones
360 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 coordinates
Latitude & Longitude
Source: worldwind.arc.nasa.gov
Geographic Coordinates
Latitude (like a ladder) – lines going east-west
that measure north/south
Longitude (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
Climate is the sum of all weather across time. Climate
cannot predict the weather.
World average annual temperature: 59°F
Lima, Ohio, annual average temperature: 59°F
Lima, Peru, annual average temperature: 59°F
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%
Permanent
gases
Variable gases
Ch4
O3 = ozone
Ch4 = methane
CO = carbon monoxide
CO2 = 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)
Atomic Weights
Hydrogen = 1
Carbon = 12
Nitrogen = 14
Oxygen = 16
Sulfur = 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
N2 O
Source: Globalwarmingweb.com
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-radiation
Mostly 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 Rules
Land 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
Lower energy level
Higher 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 Cycle
Hydrocarbon 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 feet
wet air = 5.0 degrees/1,000 feet
Russell’s ePort
Coldest Air in Lower 48 States
Big Piney, Montana -- 70 degrees F below zero
Peter’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 storage
Solid (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 factors
For 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 Index
pages 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
3-5
6-7
8-10
11-15
Low > 60 minutes to burn
Moderate 40-60 minutes
High 25-40 minutes
Very High 10-15 minutes
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