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Duane Friend
Extension Educator
University of Illinois Extension
If you would like a copy of this
power point
 Send me an email at:
[email protected]
Weather
 Why do we have seasons?
 How the atmosphere works
 Wind and air pressure
 Clouds
 Stormy Weather
 Some basic forecasting by looking at weather
The Earth and Seasons
 The Earth tilts on its axis
 As the Earth moves around the sun,
this changes the angle that the sun
hits the Earth’s surface
 This changes the amount of energy
the Earth’s surface receives
http://www.physicalgeography.net/
The more Direct the Sun Angle, the
more concentrated the Heating
http://www.physicalgeography.net
Earth’s Atmosphere
 Made up of mostly nitrogen and oxygen
 Half of atmosphere is within first 4 miles
 Has particulates (small solids and liquids, which are
needed in small amounts)
 Small amounts of trace gases that include greenhouse gases
 In general, temperature decreases with elevation in lower
levels
What makes the Sky Blue?
 Shorter wavelengths of visible light (violets/blues) gets
scattered by air molecules, sending the color off in all
directions.
http://www.physicalgeography.net/fundamentals/7f.html
Incoming Solar Radiation
http://www.physicalgeography.net/fundamentals/7f.html
What comes in eventually goes out
30
+
6
+
64 = 100
http://www.physicalgeography.net/fundamentals/7i.html
Greenhouse Effect
 The Greenhouse Effect is a natural process (we will
talk about the Enhanced Greenhouse Effect and
Global Warming later)
 Earth’s current average temperature is 59 degrees F.
Without the effect, it would be 5 degrees F.
 It occurs when greenhouse gases absorb energy trying
to escape to space, and redirects most of it back to
Earth.
Air Pressure and Winds
 Air pressure at sea level is almost 15 pounds per square
inch
 Air pressure decreases with height
 Air pressure varies due to temperature
and dynamic forces in atmosphere
http://www.physicalgeography.net/fundamentals/7d.html
Air Pressure variations
 Thermal- warm surface temperatures = lower pressure
Cold surface temperatures = higher pressures
 Dynamic- Rising air = lower pressure
Sinking air = higher pressure
http://www.physicalgeography.net/fundamentals/7n.html
Air pressure and wind
 Winds blow from high to low
 Earths rotation changes this a bit at the surface
http://www.physicalgeography.net/fundamentals/7n.html
Large Belts of High and Low
Pressure
(Courtesy NASA JPL)
The greater the pressure change,
the stronger the wind
 Close isobars of air pressure means there’s a strong
wind in that area.
http://www.physicalgeography.net/fundamentals/7n.html
http://www.physicalgeography.net/fundamentals/7r.html
Idealized Mid Latitude Cyclone/Low
Pressure System
http://www.physicalgeography.net/fundamentals/7s.html
Weather Associated with Fronts
 Prior to warm front passage: Cool temperatures, wind
from southeast or south, pressure decreasing,
increasing cloudiness with potential for extended
period of precipitation
 After warm front passage: Warmer temperatures, wind
shift to southwest, pressure remains steady, skies clear
Weather Associated with Fronts
 Prior to cold front passage: Warm/moderate
temperatures, relatively clear skies with increasing
cloudiness in vicinity of front. Winds out of south,
west, or southwest
 While front is passing: drop in air pressure, brief
intense precipitation
 After passage: Cool/cold temperatures, pressure
increases, skies clear, winds from north or northwest
Clouds
 3 main forms- Cumulus, Stratus and Cirrus
 Alto prefix- mid-level cloud
 Nimbo or Nimbus- Precipitation
Cloud formation
 Water vapor has to condense onto small water
attracting particles like dust, smoke or pollen
 These tiny droplets collide to make larger droplets
Cloud Pictures
 The following photos came from the Plymouth State
University Meteorology Program
Violent Weather
4 categories of thunderstorms
 Single cell
 Multi cell
 Multi cell (squall line)
 Supercell
Single Cell
 Forms from convective activity
 May contain brief intense rain, lightning, small hail
 Brief- only 20-30 minutes in length
Multicell line
 As one cell builds, downdraft creates additional
updraft, creating another adjoining cell May be several cells lined up one behind the other
(Training effect)
 Creates potential heavy rain, small hail, lighting, weak
tornadoes
Multi cell line (Squall Line)
 Multiple cells, moving side by side
 May have a “gust front” preceed it
 Potential for intense rain, hail, lightning, weak
tornadoes
Supercell
 Contains 5-15 mile wide rotating column of air
 Also called “mesocyclone”
 Potential for heavy rain, large hail, lots of
lightning, and strong tornadoes
 May last for hours
 Can develop along a dryline
Dryline/Supercell development
 Dryline develops in warm sector, between cold and
warm front
 Hot, dry air overrides warm, moist air, creating a cap
cT air
cT “cap” prevents mT air from
rising
mT air
Once Cap is Punched Through
 Air is extremely unstable- will ascend at upwards of
150-200 miles per hour
 Rotation develops due to wind shear
Lightning
Formation of charge
 Cloud droplets form from condensation and
collision
 Droplets are supercooled-start to freeze around -
100 C
 In updraft, ice collides with water that freezes-
creates graupel
Charge formation
 As graupel collides with other ice and water,
charge is transferred between particles
 Graupel becomes negatively charged (especially if
temperatures are -10 C or colder)
Charge formation
 Negative charges build up near base of cloud
 Positive charge induced from ground
 Electric field between cloud and ground up to 10’s
of thousand’s of volts
 Ionized path created between cloud and ground
must first be created- called a stepped leaderstarts from cloud and follows path of least
resistance
 As stepped leader gets to within 150 feet of
ground, it meets a leader coming up from the
ground, to complete path
 Negative discharge occurs
 Discharge may be repeated up to 4 times
 Each lasts about 30 microseconds
 Peak power around 1012 watts
 Positive charges can be pushed into upper parts of
cloud, especially anvil
 Can create Positive cloud/ground strikes
 More powerful, longer duration than negative
strikes
 Air from strike heated to over 40,000 degrees F
 Creates shock wave which disintegrates
into…………
THUNDER
Thunder
 Sound “rolls or rumbles” due to:
 Length of lightning bolt- sound travels 1/5 mile per
second- sound from part of bolt closest to you will reach
your ears before the farthest part of the bolt
 Echoing off of clouds and other obstacles
Other lightning types?
 Sheet lightning- lightning bolt obscured by clouds
(not a sheet of electricity)
 “Heat” lighting- lightning bolt below horizon
(not formed from heat)
Ball Lightning
 Very rare
 Little known about how/why it occurs
Lightning Safety
 As of late August, there have been 20
confirmed lightning deaths in 2011 in the US.
Before Lightning Strikes...
If you can hear thunder, you are close enough to the storm
to be struck by lightning. Go to safe shelter immediately!
When a Storm Approaches...
Find shelter in a building or car. Keep car windows closed
and avoid convertibles.
Telephone lines and metal pipes can conduct electricity.
Unplug appliances and turn off the air conditioner. Avoid
using the telephone or any electrical appliances.
Avoid taking a bath or shower, or running water for any
other purpose.
If Caught Outside...
If you are in the woods, take shelter under the shorter
trees.
If you are boating or swimming, get to land and find
shelter immediately! If you can’t make it to land, crouch
down in the boat, away from metal if possible.
Protect Yourself Outside...
Go to a low-lying, open place away from trees, poles, or
metal objects.
Make sure the place you pick is not subject to flooding.
Be a Very Small Target!
Squat low to the ground. Place your hands on your knees
with your head between them. Make yourself the smallest
target possible.
Do not lie flat on the ground -- this will make you a larger
target!
After the Storm Passes...
Stay away from storm-damaged areas.
Listen to the radio for information and instructions.
If Someone is Struck by Lightning...
People struck by lightning carry no electrical charge and
can be handled safely.
Call for help. Get someone to dial 9-1-1 or your local
Emergency Medical Services (EMS) number.
The injured person has received an electrical shock and
may be burned, both where they were struck and where
the electricity left their body. Check for burns in both
places.
Give first aid if trained to do so.
Tornadoes
 Need warm, moisture laden air at low levels
 Wind shear aloft- winds moving at different directions
and speeds
 Much the same conditions needed as for a supercell-
why they are often associated with them
Tornado statistics
 Maximum Doppler estimated wind speed- over 300
mph
 Can range in size from a few feet to almost a mile wide
 Majority of tornadoes are weak (EF 1)
Predicting Weather
 Can use things like clouds, wind direction, pressure to
make short term predictions
Using Clouds to Predict Weather
 Cumulus clouds with no growth = fair weather
 Cirrostratus creating rainbow around sun =
approaching precipitation
 Altocumulus (mackerel sky) = approaching warm
front
 Cirrus = fair weather
Using Air Pressure to Predict
Weather
 Rapidly falling air pressure- Expect stormy conditions
within 24 hours
 Slowly falling air pressure- Expect increase in
cloudiness, potential for precipitation
 Rapidly rising air pressure- Expect period of cold
temperatures and fair skies
Using Winds to Predict Weather
 Strong SE winds- Good chance of warmer weather within
next 36 hours
 Strong SE to E winds- Expect extended period of cold
temperatures and clouds/precipitation
 Strong NW wind- Expect 1-2 days of cold and dry weather
 Strong SW wind- Expect clouds/precipitation followed by
colder temperatures
Illinois Climate
Past, Present, and Future
Slide Credits
 Illinois State Water Survey
 Illinois State Museum
 Dr. Jim Hansen, Columbia University
Climate Tipping Points presentation
Outline
 Illinois’ climate history
 Current Illinois climate
 Future Illinois climate
 Climate affects on vegetation, wildlife, etc
Climate changes
 During that time, what is now Illinois moved from
south of the Equator to close to its current position,
changing from a tropical climate to dry, cool desert , to
boreal forest
Land Areas 65 Million Years Ago
Courtesy Dr. Jim Hansen, Columbia University
Courtesy Dr. Jim Hansen, Columbia University
Pleistocene and Glaciers
 From about 1.8 million years ago to about 10,000 years
ago, Illinois has been reshaped by several glacial
episodes. Climate during glacial episodes in Illinois
would have been cool and wet, while interglacial
periods would have been as warm or warmer than
present.
Photo courtesy USGS
Extent of Glaciation in
Illinois
Period
interglacial
10,000 B.C.
Wisconsin glacial
interglacial
Illinoian
glacial
interglacial
Kansan
glacial
interglacial
Nebraskan glacial
Illinois Climate 15,000 years ago
Cool Tundra
 Near the ice, Illinois would have had a cool boreal
forest, with spruce and other trees prevalent.
 These forests expanded and contracted as ice ages
grew and waned.
Short Faced Bear
Courtesy Illinois State Museum
Muskox about to be Eaten
Courtesy Illinois State Museum
Movement of vegetation
 Starting about 14,000 years ago, boreal forests moved
north as the climate warmed, replaced to the south by
deciduous forests.
 Grasslands replaced forests as climate continued to
warm from about 10,000 to 8,000 years ago
Movement of Prairies
 Boundaries of prairies and forest have changed –
prairies extended as far as Ohio and Pennsylvania
during a warmer climate several thousand years
ago.
 Forests came into the
southern prairie during
the Little Ice Age,
1300-1850
Map of Prairie Peninsula by Edgar Transeau
Prairie illustrated in dark brown
What caused the Prairie Peninsula?
 Extreme droughts periodically have occurred in this
area
 Forested areas have moisture more evenly spread
throughout the year
 Does not explain it entirely
What Else?
 The area is mostly flat
 Periodic fires kept tree growth in check
 Fires ignited by Lightning, humans
Human induced Prairie Fires
 The Miami’s hunt them at the end of autumn in
the following manner: When they see a herd they
gather in great numbers and set fire to the grass
everywhere around these animals except some
passage which they leave on purpose and where
they take post with their bows and arrows. The
buffalo, seeking to escape the fire are thus
compelled to pass near these Indians, who
sometimes kill as many as a hundred and twenty
in a day, all of which they distribute according to
the wants of the families . . .(Hennepin 1880)."
From Illinois Dept. of Natural Resources
Average
Annual
Precipitation
Average
Annual
High
Temperature
Average
Annual
Low
Temperature
Average
Annual
Snowfall
Average
Growing
Season
Climate and soils
 Illinois’ recent glaciation (yes I said recent), cold
winter, plus prairie grass coverage over most of the
state has created highly productive soils.
Soils and Climate
 Cold winters inhibit microbial decomposition of
soil organic matter
 Prairie plant root systems were massive and
fibrous
 Newly formed soils have a lot of
minerals/nutrients in A horizon
 = lots of organic matter and nutrients for plants!
Microclimates
affected by
landforms
Future Climate in IllinoisWhat will it be?
 Climates naturally fluctuate
 Human created inputs affect this change
 How to predict what climate will become
Variations Occur on Smaller
Scales
Human Induced Climate Change
 Increase in Greenhouse gases leading to Global
Warming
 What are the consequences? That’s the question!
 Computer modeling used to predict what may happen
Natural “Greenhouse” Effect
Adapted from NOAA
Global Warming
 An increase in greenhouse gases increases the
retention time of heat within the atmosphere
Global Warming
 When additional greenhouse gases are added to the
atmosphere, this increases the length of time it takes
for heat to escape, thus raising temperature in the
lower atmosphere = Global Warming
Greenhouse gases
 Carbon Dioxide
 Methane
 Nitrous Oxides
 Chloroflorocarbons
How the Earth Reacts to more
GHG’s
 Cold ocean waters absorbs some of the increase in
atmospheric CO2 (but only so much)
 Methane is cleansed from the atmosphere, but does
not do this as quickly as it is produced
 Nitrous oxides have long atmospheric lifetimes- up to
120 years. It is eventually dissociated by UV radiation
in the stratosphere
Whats the Result
 Levels of Atmospheric Greenhouse Gases are rising.
What are the consequences?
 Rising sea levels?
 Weather pattern changes?
 Ocean circulation changes?
 IT’S NOT JUST A THEORY---THE EARTH HAS TO
REACT TO THE CHANGE IN GREENHOUSE GASES
Earth’s history provides important
information on global warming.
Courtesy Dr. Jim Hansen, Columbia University
Surface Melt on Greenland
Melt
descending
into a moulin,
a vertical
shaft
carrying water
to ice sheet
base.
Source: Roger Braithwaite,
University of Manchester (UK)
Illinois State Water Survey
Illinois State Water Survey
From :Climate Change Impacts on the United States
The Potential Consequences of Climate Variability and Change
By the National Assessment Synthesis Team, US Global Change Research Program
36
Mild Winters = SOM loss
 Warmer temperatures would allow soil microbial
activity to continue to decompose soil organic matter,
instead of shutting down.
Study of soil carbon and temperature in
England
 A recent study of England's soils suggests they
have been losing carbon at the rate of four million
tons a year for the past 25 years
 In the past 25 years the average temperature has
increased by almost 1 degree Fahrenheit. Warmer
soils are believed to have encouraged greater
microbial activity and more rapid decomposition
of soil organic matter.
Bellamy, P. H., and Co-authors, 2005: Carbon losses from all soils across England and Wales 1978-2003.
Nature, 437, 245-248.
SOM and precipitation
 In general, soil organic matter is increased with
elevated levels of soil moisture.
 This is the result of greater biomass production, which
provides more residues, and thus more potential food
for soil microbes.
Double Whammy?
 Milder winter = more SOM decomposition
 More drought = less SOM production
How would increased global warming affect
soil organic matter and carbon cycling?
 Microbial activity greatly influenced by moisture and
temperature
Great Lakes species favoring cool climates are
shifting their ranges up in elevation and to the north.
Plant and animal communities adapted to warm
climates are expanding. Cool adapted tree species
such as sugar maple and paper birch are
projected to lose habitat in the U.S. and
shift largely to Canada. More southern
species such as oaks, hickories and pines
may see an expansion of potential habitats
Source: National Park Service
Arctic Change:
Future loss of Arctic
sea ice could result
in a loss of 2/3 of
the world's polar
bears within 50
years.
Source: U.S.
Geological Survey
www.usgs.gov/newsroom/sp
ecial/polar%5Fbears/
Images:
Sea Ice: Claire Parkinson &
Robert Taylor
Polar Bears: Unknown
Research shows wood ticks, wild turkeys,
badger, opossum, and flying squirrels are
extending their
ranges north. Warming climate may also be
contributing to increasing range of gypsy
moths and other exotic insect species.
Source: National Park Service
Distribution of fish will change according to
the temperature of water. Warm water fish
such as bass will expand northward, while
trout and other cold water fish will
decrease
Source: National Park Service
"We’re seeing northern range shifts of lots of
birds and butterflies," said Dr. Camille
Parmesan, a professor of conservation
biology at the University of Texas and a
member of the United Nations panel on
climate change
Potential Effects of Global Warming in
Illinois Farm Ponds
 If average summer temperatures
increase, this is increase water
temperatures in farm ponds,
decreasing dissolved oxygen levels.
 Increased aeration may be needed to
avoid fish kills.
Global Dimming
Pollutants in the form of aerosols are believed to be
reducing the amount of sunlight reaching earths
surface. Estimates of the reduction range from 10 to 30
percent.
This reduction masks the effects of global warming. As
more efforts are made to reduce air pollution, global
warming may increase at a faster rate.
From Dimming the Sun, NOVA , PBS Online
Can we have another Ice Age?
 Earth-Sun relationship seems to trigger recent glacial
episodes
 Based on earth’s axis tilt, distance from sun, and
wobble of axis, working on approximately 100,000 year
cycles.
What makes “Natural” Climate
Change Occur
http://www.physicalgeography.net/fundamentals/7y.html
Milankovic Cycles
 Change in earths orbit
 Change in earths tilt
 Earth’s wobble on its axis
Earths orbit
 Changes from circular to more elliptical over about
100,000 year cycle
 More elliptical orbit means earth receives less energy
during that time
Earth’s Tilt Changes
 Varies from about 22.1 to 24.5 degrees
 When more vertical, polar areas
receive less sunlight
http://www.physicalgeography.net/fundamentals/7y.html
Axis wobble changes the time of year when
the N. Hemisphere is pointing towards the
Sun
 Currently, N. Hemisphere is
tilted towards the sun when the
Earth is farthest away (during our
summer) = shorter winters for us
 Wobble will cause N.
Hemisphere to be tilted away from
the sun when earth is farthest
from the sun (during our winter)
in about another 13,000 years,
= longer winters for us
http://www.physicalgeography.net/fundamentals/7y.html
Summary
 Climate is in constant change
 If change is rapid, species may not be able to adapt
 If we can’t manage the change, we can only manage the
consequences