The Nature of Weather and

Climate

Steven QuiringDepartment of Geography

Texas A&M University

El Camino Real Texas Master Naturalist Chapter

April 14, 2009

Outline

• Climate Controls

– Precipitation and clouds

– Temperature

• Climate Variability in Texas- El Niño

• Climate Change

• Weather & Climate Information

Climate and Ecosystems

• Rainfall, temperature, sunshine, humidity

• Means and extremes

• Climate controls distribution of natural vegetation

• Plants in Texas must be:

– Drought tolerant (esp. in West)

– Heat tolerant

– Cold tolerant in North

Generalized Climate Regions

Figure 10.4

Major Terrestrial Biomes

Biome = A large terrestrial ecosystem characterized by specific plant & animal

communities; named based on the dominant vegetation

Figure 20.3

What is needed for precipitation to

occur?

How does the air get cooled?

A) Convergent Lifting

B) Convectional Lifting

C) Orographic Lifting

D) Frontal Lifting (Cold/Warm)

A) Cyclonic Lifting

e.g., ITCZ

• Horizontal convergence of air results in

upward vertical motion, and

precipitation

lower density

B) Convectional Lifting

b. Convective Precipitation

• Convection = upward motion of heated

air (convection cells)

• Caused by uneven surface heating or

mechanical turbulence

• Convective precipitation is short, intense

events

• Can be scattered, or organized (squall

line, tropical cyclone)

Convection over Florida

Figure 8.8

b. Convective Precipitation

• If the air is moist, the release of latent heat will ensure that the parcel of air remains warmer than the surrounding air

• If conditions remain favorable, the rising thermal will grow into a thunderstorm

C) Orographic Lifting

Figure 8.9

c. Orographic Lifting

• Warm moist air is forced over a mountain barrier

• it cools adiabatically [adiabatic process = air

temperature changes due to changes in

atmospheric pressure]

• at the LCL, condensation (and often precipitation)

occurs

Figure 8.10

C) Orographic

Lifting

Orographic Lifting

D) Frontal Lifting

• Cold Fronts

– Cold air forces warm air aloft

• Warm Fronts

– Warm air moves up and over cold air

Cold Front

Figure 8.11

D. Frontal Lifiting

• Frontal Uplift - air can be forced upward is through the

movement of air masses

• Air masses = a large body of air, with a set of relatively

uniform temperature and moisture properties

Cold Front

and

Squall Line

Figure 8.12

Warm Front

Figure 8.13

To get precipitation, you need:

1) Moisture in the atmosphere

2) Cloud condensation nuclei

3) Atmospheric lifting mechanism

– cause water vapor to cool & condense

– 4 basic mechanisms

What Controls Precipitation?

• Cool the air until it is ‘saturated’

• Water vapor condenses onto tiny

particles as a liquid or solid

• Precipitation forms when:

– enough moisture condenses to start

droplets falling and colliding, or

– the air cools enough to start forming ice

Cloud & Rain Formation

Figure 7.20

Growth of cloud droplets: 1) condensation; 2) collision-

coalescence; 3) ice crystal growth (Bergeron process)

Cloud Types and

Identification

Figure 7.23

19000 ft

6000 to 19000 ft

< 6000 ft

Named based on:

a) Height

b) Shape

Figure 3.2

• Layers based on:

– Composition

– Temperature

– Function

Profile of

Atmosphere

Cirrus = thin and wispy

Figure 7.23

Composed of ice crystals; average thickness = ~1 mi

Stratus = flat clouds in layers

Figure 7.23

Cumulus = puffy clouds in heaps

Figure 7.23

Nimbostratus = rain

Figure 7.23

Cumulonimbus =

thunderstorm

Figure 7.23

Cirrostratus

Figure 7.23

Altocumulus

Figure 7.23

Altostratus

Figure 7.23

Advection Fog

Figure 7.25

Annual Precipitation

January Precipitation

February Precipitation

March Precipitation

April Precipitation

May Precipitation

June Precipitation

July Precipitation

August Precipitation

September Precipitation

October Precipitation

November Precipitation

December Precipitation

What controls temperature?

Energy Pathways

Figure 4.1

Solar Energy:

Electromagnetic Spectrum

Fig. 2.8

Solar constant = 1372 W m-2

Solar Energy:

Electromagnetic Spectrum

McKnight and Hess, 2004

8% 47% 45%

Principal Temperature Controls

1) Latitude

Amount of solar radiation

2) Altitude

High altitude has greater daily range, lower annual average

3) Cloud Cover

High albedo = moderate temperatures (cooler days, warmer nights)

4) Land/water (continental vs. maritime)

Altitude

• Lower density reduced ability to

absorb and radiate infrared radiation

• Higher altitudes solar radiation more

intense

• Result = lower avg. temperatures,

greater nightime cooling, larger daily

temperature range

Cloud Cover

• Clouds lower daily maximum

temperatures and raise nighttime

minimum temperatures. Why?

– Night – delay release of LW radiation

– Day – reflect insolation

Clouds and Temperature

Figure 4.7

Stratus (90% albedo)

Cirrus(50% albedo)

Land and Water Contrasts

5) Low albedo5) High albedo

January Average Daily Maximum

January Average Daily Minimum

July Average Daily Maximum

July Average Daily Minimum

What are the main causes of

climate variability?

1 MONTH 3 MONTHS

6 MONTHS 18 MONTHS

Ending April 13, 2009

Ending April 13, 2009 Ending April 13, 2009

Ending April 13, 2009

TAMU OSC

EXCEPTIONAL

EXTREME

SEVERE

MODERATE

ABNORMALLY DRY

NO DROUGHT

Climate Variability: El Niño

(ENSO)

Normal SSTs in the Central Pacific

ENSO

• In the late 1890s, fishermen along the coast of Peru begin to realize that every 2 to 10 years, with an average frequency of 7 years, there is a failure of the anchovy catch

• Anchovies feed on phytoplankton which, in turn, feed on nutrients from cold, upwelling waters

ENSO

• The loss of the anchovy catch was

termed an El Niño event – literally, the

male child although, in this case, it refers

to the Christ Child since the loss occurs in

the Southern Hemisphere Summer

(around Christmas)

Later references sometimes refer to this

event as a Warm Phase, although El

Niño is still used

El Niño Conditions

From International Research Institute for Climate Prediction

El Niño SSTs in the Central Pacific

Sea Surface Temperature Anomalies: El Nino Years

La Niña Conditions

La Niña SSTs in the Central Pacific

Sea Surface Temperature Anomalies: La Nina Years

U.S. & Global Weather

Anomalies

El Nino Cool-Season Precipitation

El Nino Cool-Season Temperature

La Nina Cool-Season Precipitation

La Nina Cool-Season Temperature

Current Conditions

http://www.cpc.noaa.gov/products/analysis_monitoring/enso_update/sstanim.shtml

Niño Region SST Departures (oC)

Recent Evolution

The latest weekly SST departures are:

Niño 4 0.0ºC

Niño 3.4 -0.1ºC

Niño 3 0.1ºC

Niño 1+2 0.1ºC

U.S. Temperature and Precipitation Departures

During the Last 90 Days

90-day (ending 12 Apr 2009) % of

average precipitation

90-day (ending 11 Apr 2009)

temperature departures (degree C)

These seasonal outlooks combine long-term trends, soil

moisture, and some aspects of La Niña.

U. S. Seasonal Outlooks

April – June 2009

Temperature Precipitation

What evidence is there of climate

change?

State of the Climate (through 2007)

• 2007 = 5th warmest year in the 120+ year instrumental record

[2005/1998 = tied for warmest, 2002 = 2nd

warmest, 2003 = 3rd warmest, 2004 = 4th

warmest]

• Global temperatures were +0.5°C above the 1961-1990 mean

• 10 warmest years observed in the instrumental record (begins in 1880) have all occurred since 1995

2007 Temperature Anomalies

Temperature Trends

• Temperature rise of about 0.17C/decade (since

1979)

• Rate of warming is about 3X greater since 1979

– consider T of 1.5 C in last 10,000 years and T of

1.0 C in last 1,000 years

Climate Trends• Diurnal temperature range has decreased (min T are

warming twice as fast as max T)

• Precipitation trend = +5–10% for 30–85°N since 1900

• Sea level rise = +2.8 mm/yr since 1993

• Snow cover extent has generally decreased

• Earlier spring melt, later fall frost = longer growing

season

Climate Change 2007:

The Physical Basis

IPCC Summary for

Policy Makers

Earlier spring melt, later fall frost = longer growing season

Sea Level

Rise

•Since 1996, rate of loss from Greenland ice sheet has increased by 67%

•If all of the Greenland ice sheet melted, global sea-level would rise 23 ft

(7 m)

•Annually, it contributes about 0.5 mm (0.02 in.) to global sea-level rise

Shrinking glaciers

What is causing the climate to

change?

Causes of Climate Change

1) Natural mechanisms:

-variations in solar output

-orbital variations

-movement of continents

-atmosphere/ocean variability

-volcanic activity

2) Human mechanisms:

-land use/land cover change (e.g.,

deforestation)

-changing atmospheric chemistry

(greenhouse gases)

Carbon Dioxide• Radiative forcing of

greenhouse gases is

due primarily (~64%)

to CO2

• Concentrations have

increased from 330 to

383 ppm in the last 30

years

• Rate of increase

since Industrial

Revolution

unprecedented in the

last 10,000 years

How is the climate going to

change?

General Circulation Models

(GCMs)

• GCMs are the best tool for projecting the

response of Earth systems to human (&

natural) influences

GCM Projections• The projected rise in air temperature is 1.8°C

to 4.0°C by the year 2100 (best estimate ~3.0°C)

• Precipitation will likely increase (decrease) in some regions 10 to 20%

• Decrease in snow cover and sea-ice depth and extent

• More frequent and intense heat waves, droughts, and heavy precipitation

• Tropical cyclones may be more intense(IPCC, FAR SPM)

- all models produce maximum warming in high northern latitudes

-warming is largest in late autumn and early winter, due to sea ice

forming later

Climate Change and Drought in

Texas:

Past vs. Future

John Nielsen-Gammon

Texas State Climatologist

Texas A&M University

The Impact of Global Warming in Texas:

http://www.texasclimate.org/

PANHANDLE

AND PLAINS

FAR WEST

TEXAS

WEST

CENTRAL

TEXAS

SOUTH

CENTRAL

TEXAS

SOUTH

TEXAS

SOUTHEAST

TEXAS

NORTH

CENTRAL

TEXAS

EAST

TEXAS

Dec-Feb Temperatures

-3

-2

-1

0

1

2

3

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year

Ave

ra

ge

Te

mp

era

ture

(F)

Panhandle and Plains Far West Texas West Central Texas South Central Texas

North Central Texas East Texas South Texas Southeast Texas

Mar-Apr, Oct-Nov Temperature

-3

-2

-1

0

1

2

3

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year

Te

mp

era

ture

(F)

Panhandle and Plains Far West Texas West Central Texas South Central Texas

North Central Texas East Texas South Texas Southeast Texas

May-Sept Temperature

-3

-2

-1

0

1

2

3

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Year

Te

mp

era

ture

(F)

Panhandle and Plains Far West Texas West Central Texas South Central Texas

North Central Texas East Texas South Texas Southeast Texas

6

5

4

3

2

1

0

-1

Te

mp

era

ture

Chang

e (

F)

2060205020402030202020102000

Texas A1B Projections

Climate model projections: + 4 °F by 2050

Temperature Projections for Texas

Precipitation trends at century-

long USHCN stations

Blue: Increasing

Precipitation Red:

Decreasing Precipitation

1901-

19251926-

1950

1951-

1975

1976-

2000

Fraction of months below 20th percentile of PDF, 12-month

precip

We were spoiled

during 1976-2000!

December-March Smoothed Precipitation

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1899

1902

1905

1908

1911

1914

1917

1920

1923

1926

1929

1932

1935

1938

1941

1944

1947

1950

1953

1956

1959

1962

1965

1968

1971

1974

1977

1980

1983

1986

1989

1992

1995

1998

2001

Year

Fra

cti

on

of

Lo

ng

-Te

rm

Me

an

Pre

cip

Panhandle and Plains Far West Texas West Central Texas South Central Texas

North Central Texas East Texas South Texas Southeast Texas

April-July Smoothed Precipitation

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1899

1902

1905

1908

1911

1914

1917

1920

1923

1926

1929

1932

1935

1938

1941

1944

1947

1950

1953

1956

1959

1962

1965

1968

1971

1974

1977

1980

1983

1986

1989

1992

1995

1998

2001

Year

Fra

cti

on

of

Lo

ng

-Te

rm

Me

an

Pre

cip

Panhandle and Plains Far West Texas West Central Texas South Central Texas

North Central Texas East Texas South Texas Southeast Texas

August-November Smoothed Precipitation

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

1899

1902

1905

1908

1911

1914

1917

1920

1923

1926

1929

1932

1935

1938

1941

1944

1947

1950

1953

1956

1959

1962

1965

1968

1971

1974

1977

1980

1983

1986

1989

1992

1995

1998

2001

Year

Fra

cti

on

of

Lo

ng

-Te

rm

Me

an

Pre

cip

Panhandle and Plains Far West Texas West Central Texas South Central Texas

North Central Texas East Texas South Texas Southeast Texas

-20

-10

0

10

20

Perc

enta

ge P

recip

itatio

n C

han

ge

2060205020402030202020102000

Texas A1B Projections

Climate model projections: probably drier by

2050

Precipitation Projections for Texas

• IPCC estimates that global sea level will

rise 0.18 to 0.59 m (7 to 23 in.) by 2100

• However, this estimate does not consider

the large changes in ice sheet mass flux

that have been observed since 2003

• Actual sea level changes may by larger

than those predicted by the IPCC

Sea Level Rise

Sea Level Rise

• Beach erosion

• Loss of agricultural land

• Loss of thousands of kilometers of land

• Displacement of millions of coastal residents

http://www.cresis.ku.edu/research/data/sea_level_rise/index.html

1 m Sea-Level Rise

Climate Change Summary

• Yes, global surface temperatures are

rising due to human activities

• Future = certainly warmer, maybe less

rain, definitely more evaporation

• That scenario could easily happen (and

has) even without global warming

• Year-to-year changes strongly driven by

nature

Headline: Hundreds Attend

Global Warming Protest

Weather and Climate

Resourceshttp://atmo.tamu.edu/osc

– Office of the State Climatologist, Texas

• www.met.tamu.edu/class/wflm– Online Weather Forecasting learning modules

• meted.ucar.edu– Online training for weather forecasters

• www.cdc.noaa.gov– Monitoring Earth’s climate on medium range to

interannual time scales

Weather and Climate

Resources• www.srh.noaa.gov/hgx

– Warnings, short-range forecasts, radar

• www.tceq.state.tx.us/nav/data/air_met_data.h

tml

– Ozone and air quality (current and historic)

• weather.msfc.nasa.gov

– Real-time satellite image browser

• www.txwin.net

– TX Water Information Network (drought, etc.)

Help Improve Local Monitoring

• Community Collaborative Rain, Hail, and

Snow Network (CoCoRaHS)

• http://www.cocorahs.org/

• Volunteer high-density rain gauge

monitoring network

• More volunteers needed in Texas!

Local Monitoring Tools

• Office of the State Climatologist, Texas

• http://atmo.tamu.edu/osc

• Weekly/monthly climate reports

• Climate monitoring tools under

development

The End

• Contact Info:

– Steven Quiring, Texas A&M University

– squiring@tamu.edu

– http://geog.tamu.edu/~squiring/

– (979) 458-1712