Weather Observers - University Of Illinois · Weather Observers Duane Friend University of Illinois Extension . What Will be Covered •Why we have seasons •The ... •Clouds and

Weather Observers

Duane Friend

University of Illinois Extension

Weather Observers Duane Friend

University of Illinois Extension

What Will be Covered

• Why we have seasons

• The Composition of the Atmosphere (Why is the sky blue?)

• Heat and Temperature (What does a “Feels Like” temperature mean?)


• Air Pressure and Winds (Why does most of our storms come from the west?)

• Clouds and Precipitation (What do different clouds mean for future weather?)

• Climate and Weather (How do scientists predict future climate, and how accurate are they?)


• Volunteer Precipitation Monitoring- Training in the Community Collaborative Rain, Hail, and Snow (CoCoRaHS) monitoring program

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 at different latitudes

http://www.physicalgeography.net/fundamentals/7f.html

Courtesy NASA/NOAA

23.50 N 23.5 0 S



Noon Sun angle at 40 degrees North Latitude

73.50

500

26.50

Sun

Sun

June Solstice

Equinoxes

December Solstice

During the year, the earth gets closer or farther from the sun, but this does not have a great effect on seasonality

In fact, the earth is closest to the sun

at a time you may not expect-


Daylight Hours Have a Small Affect on Seasonality

• Through winter and spring, Jacksonville, IL gains about 2 to 3 minutes of daylight per day, with the longest daylight experienced on the first day of summer (approximately 15 hours)

• Through summer and fall, we lose 2-3 minutes of daylight per day, with the shortest daylight experienced on the first day of winter (9 hours 21 minutes)

Fairbanks, Alaska

• Fairbanks, Alaska, gains 6-7 minutes of daylight per day during winter and spring, with a daylight length of 21 hours 50 minutes on the first day of

summer

• They lose 6-7 minutes of daylight during summer and fall, and have only 3 hours 41 minutes of daylight on the first day of winter

Daylight Length Dependent on Latitude

• At Equator, daylight is always 12 hours

• Daylight hours change more rapidly the farther you move from the Equator.

• At the poles, the sun is up for 6 months or below the horizon for 6 months

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, such as carbon dioxide and methane

• In general, temperature decreases with elevation in lower levels (on average, about 3 ½ degrees Fahrenheit per 1000 feet)


Temperature decreases

Temperature increases

Temperature decreases

Where “Weather” occurs

Ozone here- Most UV Stopped

Gamma and X Rays Stopped here

Half of Atmosphere Below this point

Sunlight (Solar Energy)

Sunlight Travels as a Wave

• There is an infinite range of wavelengths of sunlight (solar energy).

• The human eye only can detect a small range of this energy- the visible spectrum.

Courtesy NASA

What humans see

http://imagine.gsfc.nasa.gov/Images/science/EM_spectrum_full.jpg

(millionths of a meter)

Majority of Sunlight Reaching Earth’s Surface is in the Visible Spectrum

Incoming Outgoing

Courtesy NASA

http://imagine.gsfc.nasa.gov/Images/science/EM_spectrum_atmosphere.jpg

What makes the Sky Blue?

• Shorter wavelengths of visible light (violets/blues) gets scattered by air molecules, sending the color off in all directions.


What Happens to All That Energy from the Sun?

Incoming Solar Radiation


What comes in eventually goes out

http://www.physicalgeography.net/fundamentals/7i.html

30 + 6 + 64 = 100%

The Earth’s Atmosphere is Mostly Heated from the Earth’s Surface

Condensation = Heat released to atmosphere

• The heat released by condensation is the single most important way heat is transferred from earth’s surface to the atmosphere.

• The release of heat from condensation can occur hundreds or thousands of miles from where the heat was picked up by evaporation

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.

Greenhouse Gases

• Gases like carbon dioxide, methane, and nitrous oxides have the ability to absorb heat that is trying to escape into space.

• The heat is released by the gases, but a lot of it is sent back towards earth instead of heading out to space.

When the heat is released, it goes out in all directions

A Lot Heads Back to Earth

What Happens if Greenhouse Gases Increase?

• Increases of Greenhouse gases have increased the Greenhouse effect, leading to warming of the lower atmosphere.

• Cause and Effect- we’ll talk about this more when we discuss Climate Change……

Things that cause temperature differences around the world

• Sun angle

• Elevation

• Daylight length

• Differences in heating from land and water

Land and Water Heating Differences

• Land heats up faster and to a greater extent than water does

• Land cools faster and to a greater extent than water does

• Water acts as a moderator of temperature.

Heat Index and Wind Chill

• The Heat Index, sometimes referred to as the apparent temperature is given in degrees Fahrenheit. The Heat Index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature.

http://www.nws.noaa.gov/glossary/index.php?word=heat+index

http://www.nws.noaa.gov/glossary/index.php?word=Fahrenheit

http://www.nws.noaa.gov/glossary/index.php?word=Fahrenheit

http://www.nws.noaa.gov/glossary/index.php?word=relative+humidity

• The NWS Windchill Temperature (WCT) index uses advances in science, technology, and computer modeling to provide an accurate, understandable, and useful formula for calculating the dangers from winter winds and freezing temperatures. The index:

• Calculates wind speed at an average height of five feet, the typical height of an adult human face

• Incorporates heat transfer theory, heat loss from the body to its surroundings, during cold and breezy/windy days

• Assumes no impact from the sun (i.e., clear night sky).

Predicting Daily Temperatures

• Numerical models are used that input current atmospheric conditions, satellite readings, etc.

• These models have been much more accurate in the last 5-10 years, and should continue to improve as computing speed increases. (More speed means more variables can be used in the model)

Air Pressure

• This is the force created by many, many air molecules

• It is not just a downward force

Air Pressure

• Air pressure at sea level is almost 15 pounds per square inch

• Air pressure decreases rapidly

with height

• Air pressure varies due to

temperature and dynamic forces

in atmosphere http://www.physicalgeography.net/fundamentals/7d.html

Aneroid Barometer

NOAA

Air Pressure and Weather

• In general, lower air pressure is related to cloudiness, or unsettled weather

• In general, higher air pressure is related to fair weather

Air Pressure variations

• Thermal- warm surface temperatures = lower pressure

• Cold surface temperatures = higher pressures

http://www.physicalgeography.net/fundamentals/7n.html

Air pressure and wind

• Winds blow from high to low

• Earths rotation changes this at the surface

• Wind is always described in terms of the direction it’s coming from



Idealized pressure and winds


What Really Happens

Stormy

Fair/Desert

Fair/Desert

Stormy

Stormy

Fair

Fair

EQUATOR

300

300

600

600

The Highs and Lows on Weather Maps are Individual Cells

• Dynamic- Rising air = lower pressure

Sinking air = higher pressure

From U. of I. Master Naturalist- Weather and Climate Chapter

The greater the pressure change, the stronger the wind

• Close isobars of air pressure means there’s a strong wind in that area.


El Nino/La Nina

• Normally, there is high pressure off the coast of South America. Winds and warm surface ocean water flows from S. America towards Australia. Deep, cold water comes up to the surface along S. America to replace the surface water that is moving away.

• During an El Nino, warm water starts flowing back towards S. America. Winds also reverse, as S. America coast becomes an area of High pressure.

“Normal”

South America Australia

Cold Water

Warm Water

El Nino Winds/Currents Reverse

Warm Water Heads Towards South America

South America

Australia

La Nina

• La Nina is similar to “normal” conditions in the Pacific, but exhibits unusually cold ocean surface temperatures near S. America

El Nino/La Nina Weather Effects

Courtesy National Weather Service

Humidity and Precipitation

Humidity

• Usually described as Relative Humidity

• This shows how much moisture is actually in the air, compared to the maximum amount the air can hold at that temperature.

Higher Temperatures Can Hold More Water Vapor

Temperature

Water Vapor

This doesn’t mean the air IS holding a lot……

Humidity Instruments

https://www.nc-climate.ncsu.edu/secc_edu/images/psychrometer.jpg

Hair Hygrometer

Source: USA TODAY research by Chad Palmer

Another Method of Describing Humidity is Looking at the Dew Point

Temperature

• At 100% Relative Humidity, the air is holding as much water vapor that it can hold at that temperature. Any excess water vapor will condense back to liquid water.

• As air cools at night, its water vapor capacity decreases. If it cools enough, it reaches its dew point temperature and produces……dew!

High Dew Points Mean Uncomfortable Conditions and Potential for Unsettled

Weather

• Watch out for dewpoints in the 50’s or 60’s in March- may mean potential for storms.

• Dew points in the 70’s during the summer could also mean potential for storms.

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 are courtesy The Cloud Appreciation Society

http://cloudappreciationsociety.org/

http://cloudappreciationsociety.org/

Cloud Pictures

• The following photos came from the Plymouth State University Meteorology Program

Precipitation

Types of Precipitation in Illinois

• Rain

• Snow

• Sleet

• Freezing Rain

• Hail

Rain

• Most rain away from equatorial regions begins as snow, and melts on the way down.

Drop Sizes and Fall Rates

• Cloud droplet = .0008 inches

– Fall rate = .03 ft/sec.

• Rain drop = .08 inches

– Fall rate 21.4 ft/sec.

Snow


Sleet


Freezing Rain


Hail

• Starts as small ice pellets, and increases in size as layers of water freeze.

Courtesy NOAA

Size of Hail Affects Speed

• BB sized hail may fall at less than 24 MPH

• Golf ball sized hail fails around 103 MPH

• Soft ball sized hail falls around 166 MPH! From: NOAA

Reading A Weather Map

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 (Location B): Cool temperatures, wind from southeast or south, pressure decreasing, increasing cloudiness with potential for extended period of precipitation

B



• After warm front passage (Location X): Warmer temperatures, wind shift to southwest, pressure remains steady, skies clear

X



• While Cold front is passing: drop in air pressure, brief intense precipitation


• After passage (Location A): Cool/cold temperatures, pressure increases, skies clear, winds from north or northwest

A http://www.physicalgeography.net/fundamentals/7s.html

If Low Pressure is North of Your Location

• Winds will shift from SE to SW to NW


If Low Pressure is South of Your Location

• Wind shift SE-E-NW

• Expect a period of steady rain/drizzle and a cold easterly wind


Other “Fronts”

• Stationary front

• A front between warm and cold air masses that is moving very slowly or not at all.


Other “Fronts”

• Occluded front

• Formed as a cold front overtakes a warm or quasi-stationary front.


Other Symbols on Weather Maps

• A “trough”

• An elongated area of relatively low atmospheric pressure


Other Symbols

• Dry line

• A boundary separating moist and dry air masses. Usually located between a warm front and cold front.


High Pressure Cells

• High pressure cells do NOT have fronts

• These will generally be associated with clear skies/fair weather

Violent Weather

• Thunderstorms

• Lightning

• Tornadoes

• Derechos

Thunderstorms

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- Training Thunderstorm

• 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

Training Thunderstorm. Courtesy National Weather Service

Updrafts and Downdrafts

• A thunderstorm's updraft can carry 8000 tons of water aloft per minute

• Rising air in smaller thunderstorms moves at speeds near 40 mph

• When rain begins to fall, they drag the air down around them and a downdraft forms. The rain also is falling into unsaturated air and so some evaporation occurs, cooling the air nearby. This rain-cooled air is now cooler than its surrounding environment and it sinks, helping to form and intensify the downdraft

National Weather Service

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

Squall Line. Courtesy National Weather Service

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

Supercell. Courtesy National Weather Service

Dryline/Supercell development

• Dryline develops in warm sector, between cold and warm front

• Hot, dry air overrides warm, moist air, creating a cap

Hot, dry Air mass

Warm, moist air mass

The hot dry air acts as a cap, preventing the warm moist air from rising for a while……

Once Cap is Punched Through

• Air is extremely unstable- will ascend at upwards of 150 miles per hour

• Rotation develops due to wind shear

Do Storms split apart after crossing a river?

• From the National Weather Service-Unfortunately, there is no proof that storms split or dissipate after they cross rivers...they can, and do, but not in a way that would indicate a pattern. There is no documented evidence that the effects of a river or lake, even a mile wide, has a significant effect on the dynamics of a thunderstorm. The scale of the river is very small when compared with the scale of a thunderstorm that extends five miles or more into the atmosphere and can range from tens of miles to hundreds of miles in diameter

Having Said That, There are Splitting Thunderstorms-

• A thunderstorm which splits into two storms which follow diverging paths (a left mover and a right mover). The left mover typically moves faster than the original storm, the right mover, slower. Of the two, the left mover is most likely to weaken and dissipate (but on rare occasions can become a very severe anticyclonic-rotating storm), while the right mover is the one most likely to reach supercell status (National Weather Service)

Derechos

Photo Courtesy National Weather Service And Brittney Misialek

Derecho Classification

• A straight line wind of at least 58 miles per hour or greater than creates a damage path of at least 240 miles

• The swaths of stronger winds within the general path of a derecho are produced by what are called downbursts

• Occur in irregularly-arranged clusters


The campus of Southern Illinois University suffered extensive damage, with nearly 100 windows blown out of residence halls. An unofficial gust to 106 mph was recorded on the roof of the Carbondale airport. This derecho travelled over 1000 miles in 24 hours.

May 2009 Derecho



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 leader- starts 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


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

• 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

Different Thunder Sounds

• http://www.ec.gc.ca/foudre-lightning/default.asp?lang=En&n=4EFD3A52-1

http://www.ec.gc.ca/foudre-lightning/default.asp?lang=En&n=4EFD3A52-1





Lightning Safety

• Twenty-three Americans died from lightning in 2013, the fewest since records began in 1940.

From: USA Today

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 Computer Simulation

• http://access.ncsa.illinois.edu/Stories/supertwister/tornado/tubecone_popup.htm

• Developed by the University of Illinois National Center for Supercomputing Applications and Lou Wicker at the National Severe Storms Lab

• In this visualization, orange spheres are rising; blue spheres are falling. Swaying cones are used to symbolize the speed and direction of the wind at ground level

http://access.ncsa.illinois.edu/Stories/supertwister/tornado/tubecone_popup.htm

http://access.ncsa.illinois.edu/Stories/supertwister/tornado/tubecone_popup.htm

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)

FUJITA SCALE DERIVED EF SCALE OPERATIONAL EF SCALE

F Number Fastest 1/4-mile

(mph) 3 Second Gust

(mph)

EF Number

3 Second Gust

(mph)

EF Number 3 Second Gust

(mph)

0 40-72 45-78 0 65-85 0 65-85

1 73-112 79-117 1 86-109 1 86-110

2 113-157 118-161 2 110-137 2 111-135

3 158-207 162-209 3 138-167 3 136-165

4 208-260 210-261 4 168-199 4 166-200

5 261-318 262-317 5 200-234 5 Over 200

Tornado safety

• Go to a small sturdy room on a lower level.

• If in a mobile home/RV, get to something safer

• If in a car, leave seat belt on and get your head as low as possible, and cover your head- don’t go to an overpass

• If no car or building available, lie flat in a depressional area, covering your head

Predicting Weather

• Can use things like clouds, wind direction, pressure to make short term predictions

Photo courtesy NOAA

http://celebrating200years.noaa.gov/foundations/weather_obs/fg3_650.html

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

NOAA

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

Climate Change

• The following information is from Dr. Don Wuebbles, Atmospheric Scientist at the University of Illinois. Dr. Wuebbles is an expert in numerical modeling of atmospheric physics and chemistry. He shares in the 2007 Nobel Peace Prize for his work with the international Intergovernmental Panel on Climate Change.

Observed and Projected changes in Climate in the

Midwest

Don Wuebbles Department of Atmospheric Sciences

University of Illinois

July 2013

The Science is Clear: Climate change is one of the most important issues facing humanity

The scientific evidence shows that our climate is changing, and that human activities are identified as the primary cause.

All major science organizations have put out strong statements about this issue.

e.g., National Academy of Sciences, American Geophysical Union, American Meteorological Society, American Physics Society, American Chemical Society, Ecological Society of America, American Assoc. Adv. Of Science

Observational

Records Clearly

Indicate a

Changing Global

Climate

The Greenhouse Effect: Sustains Life on Earth, but being Affected by Human

Activities

Natural Drivers of Climate

Variations in the Earth's

orbit (Milankovitch

effect)

Stratospheric aerosols from

energetic volcanic eruptions

Variations in the

energy received from the

sun

Human Factors in Climate

Changes in atmospheric gases

Changes in particles from burning fossil fuels and biomass

Strong evidence that the climate change occurring is primarily human induced

Human fingerprints have been identified in many aspects of climate change •Surface and vertical temperature

•Stratospheric and tropospheric

temperature change

•Height of the tropopause

•Precipitation

•Vertical structure of upper-ocean

temperature changes

•Ocean heat content

•Atmospheric moisture

•Arctic sea ice

•Sea-surface temperature changes in

hurricane formation regions

Observed Decrease in Solar Irradiance since 1978

The scientific evidence points to human activities as the

primary cause of the changing climate.

Natural processes cannot account for

observed global climate changes over

last 5 decades

• Increasing temperature

• Increasingly intense downpours

• Rising sea level

• Rapidly retreating glaciers

• Thawing permafrost

• Longer growing season

• Longer ice-free season in the ocean and on lakes and rivers

• Earlier snowmelt

• Changes in river flows

Since the 2009 U.S. Assessment: Science Shows Climate Changes Continue in U.S.

Surface Temperature Analysis • Based on NWS Cooperative Observer Network

• Potential sources of bias

– Change to electronic instrumentation in 1980s:

lowering of Tmax, raising of Tmin

– Change in typical observing time from late afternoon

to early morning: lowering of both Tmax and Tmin

– Station siting

• NCDC uses objective detection schemes to

identify shifts and estimate corrections

• New climate division data set, based on the

adjusted station data

U.S. average temperature has risen by 1.5oF since 1895; mostly since 1980

Data from NOAA NCDC

Increase occurring in all seasons

Contiguous U.S. Temperature Trends

Midwest: Increasing Trend in Temperature

Winter Spring

Summer Fall

U.S. Growing Season is Lengthening

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170

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190

1895 1910 1925 1940 1955 1970 1985 2000

Le

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th o

f G

row

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Se

aso

n

(da

ys)

Year

Observed Trends: 1991-2011 relative to 1901-1960

Midwest

Changes in Frost-Free Season relative to 1901-1960

Data from NOAA NCDC

Increasing trend: U.S. breaking many more heat records than cold records

Based on Meehl et al., Science (2009)

1800 U.S. weather stations from 1950

2011 3 to 1 2012: 10 to 1

Last 3-5 Decades: U.S. Increasing trend in Heat Waves, less Cold Waves

Midwest: no trend in Heat Waves, but less Cold Waves

171

Observed Increasing Trend in U.S. Precipitation Both in Decadal trends and 1991-2011 relative to 1901-1960

Based on NOAA NCDC data

Midwest: Increasing Trend in Precipitation

Especially Spring and Summer

Observations show major increase in very heavy precipitation events over last 50 years

defined as the heaviest 1 percent of all daily events from 1958 to 2010

Extreme Precipitation in Midwest

174

0.0

0.5

1.0

1.5

2.0

2.5

1895 1910 1925 1940 1955 1970 1985 2000

Extr

em

e P

reci

pit

atio

n In

dex

Year

Blue = 1-yr storms, highest value: 1998 Red = 5-yr storms, highest value: 2004 Green = 20-yr storms, highest value: 2008

Certain types of extreme weather events have become more frequent and intense – Heat Waves, Floods and Droughts in some regions Floods (USGS, 2011) Droughts (PHDI)

Increase: Midwest, Northeast Decrease: Southwest Increase: West, Southeast

Time series of billion dollar disasters in the U.S.

Attribution: There is a Detectable Human Influence on Recent Major Weather Events

Examples

• UK flooding in 2000

• European heat wave of 2003

• The cold U.S. of 2008

• Cold European winter 2009/2010

• Moscow heat wave of 2010

• The 2011 drought in Texas and Oklahoma

Temperature is Expected to Continue to Increase over the U.S.

Relative to 1901-1960

Future Climate Change Depends on Our Decisions about Emissions

Midwest Temperature

Changes 2041-2070

Compared to 1971-2000

High emissions scenario (A2)

Precipitation Projections: Low and High Scenarios

2070-2099 of seasonal average precipitation relative to 1971-2000

Midwest Precipitation

Changes 2041-2070

Compared to 1971-2000)

High emissions scenario (A2)

Top 2%

The Future: Increasing Tendency for Severe Precipitation Events in U.S.

Historical and projected changes in the amount of precipitation falling in the top 1% of events

Historical

High scenario

Low scenario

High scenario

Low scenario

Midwest: Severe Precipitation Events likely to increase (new CMIP5 analyses)

Historical and projected changes in the amount of precipitation falling in the top 1% of events

100%

Historical

High scenario

Low scenario

Illinois Summers Likely to be More

Like Southern U.S. by End of Century Based on summer average temperature and precipitation

Climate Change is likely to affect us in many different ways

0

10

20

30

40

50

60

70

80

1961-1990 2010-2039 2040-2069 2070-2099

Da

ys

pe

r Y

ea

r o

ve

r 9

0o

F Historical

Low emissions future

High emissions future

0

5

10

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20

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1961-1990 2010-2039 2040-2069 2070-2099

Da

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Historical



Chicago: Extreme Heat & Public Health Projected Increase in Maximum Temperatures

By end-of-century, number of days over 90oF (32oC) Low emissions: More than 2x greater than today High emissions: More than 4x greater than today

By end-of-century, number of days over 100oF (38oC) Low emissions: More than 4x as many as today High emissions: More than 15x as many as today

Heat Waves are Projected to Increase

Chicago 1995-type heat wave will become routine by end of century – as many as 3 per year by 2100

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10

15

20

25

30

35

1960 1980 2000 2020 2040 2060 2080

Nu

mb

er

of

He

at

Wa

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s p

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Dec

ad

e

Lower Emissions

Higher Emissions

Rainfall and Water Resources Heavy Rainfall Events (> 2.5 inches)

2.5” per day: approximate threshold for combined runoff-sewer overflow into Lake Michigan (can lead to beach closings)

Increases of almost 2x under lower emissions and 3x under higher

Agriculture faces increasing challenges from

heat stress, water stress, pests, diseases, and weather extremes

©Copyright

Infrastructure and Economy Less Energy Demand in Winter, but Much Greater Demand in

Summer

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1961-1990 2010-2039 2040-2069 2070-2099

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Decreased demand for gas and oil for winter heating

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1961-1990 2010-2039 2040-2069 2070-2099

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Increased demand for electricity for summer cooling

Summer Winter

We must meet the Challenge

The worst impacts can be avoided

• Avoid the unmanageable

• Manage the unavoidable

Many Pathways to Reducing Emissions

US Army Corps of Engineers

Dave Saville, courtesy of FEMA

The benefits of strong, early action on

climate change outweigh the costs

There are Many Indicators of a Changing Climate

Sea Level Rise

N.H. Snow Cover

Troposphere T Land surface air T

Marine air T

Sea surface T Ocean heat content

Specific humidity

Arctic sea ice extent

Glacier mass balance

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.

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.

Courtesy Illinois State Museum

Muskox about to be Eaten

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

Illinois Climate Now

http://www.sws.uiuc.edu/docs/watercycle/

Average Annual Precipitation

Average Annual High Temperature

Average Annual Low Temperature

Winter

2010 2010

1895

1895 1895

59

47

60

48

36

20

Spring

Fall

2010 2010

1895

78

69

Summer

1895 1895

1895 1895

2010 2010

2010 2010

5 inches 5 inches

5 inches 2.5inches

17 inches

17 inches

17 inches

10 inches

Spring Summer

Fall Winter

Future Climate in Illinois- What will it be?

• Climates naturally fluctuate

• Human created inputs affect this change

• How to predict what climate will become

Melt descending into a moulin, a vertical shaft carrying water to ice sheet base.

Source: Roger Braithwaite, University of Manchester (UK)

Surface Melt on Greenland

Computer Modeling

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

"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.

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

Conclusions • Climate is changing in the U.S. largely as a result of

human activities; these changes are likely to continue (depends on us)

• Growing season is getting longer.

• Certain types of extreme weather events are becoming more common. Trends likely to continue. – More precipitation coming as larger events.

– Heat waves are generally increasing, and will likely become longer and more severe.

– Cold waves are becoming less common.

– Increasing risk of floods and droughts in some regions.

• Sea levels are increasing and likely to increase by 1 to 4 feet over this century.

• These changes are significantly affecting the U.S.

Dr. Don Wuebbles, University of Illinois

A Sense of Hope

Our future depends on how we act to limit climate change.

Adaptation is not a choice – our choice is whether to adapt proactively or respond to the consequences.

Adaptation requires a paradigm shift, focusing on managing risks.

We can draw on our long history of responding to changing conditions in facing the challenges of climate change.

Dr. Don Wuebbles, University of Illinois

QUESTIONS?

Documents

Weather Observers - University Of Illinois · Weather Observers Duane Friend University of Illinois Extension . What Will be Covered •Why we have seasons •The ... •Clouds and