meteorology 101

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Meteorology 101

Fundamentals

of Weather

Jon Nese and Jen Carfagno

The Weather Channel

February 22, 2004

(Some)

From: www.epa.gov/aqi/2004conference/sunday/nese_

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Meteorology 101

•

• Weather and Air Quality:

Weather and Air Quality:

The Issues

Outline

•

• Basic Weather Concepts

Basic Weather Concepts

•

• The “Models”

The “Models”

•

• Weather Observations

Weather Observations

•

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Meteorology 101

Weather & Air Quality: Weather & Air Quality: Keys

Keys: : Air Air motionmotion,, cloudsclouds, and, and precipitationprecipitation..

• Wind, mixing disperse Pollutants!!

• Clouds reduce sunlight and

• Clouds reduce sunlight and slow productionslow production

of some pollutants. of some pollutants. H Hoorriizzoonnttaall:: WWiinndd V Veerrttiiccaall:: VVeerrttiiccaal l MMoottiioonnss, , mmiixxiinngg •

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Meteorology 101

Questions to Answer

•

• What controls vertical motions?

What controls vertical motions?

•

• When and where do clouds and

When and where do clouds and

precipitation form?

•

• How, why, when, where does the

How, why, when, where does the

wind blow?

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Meteorology 101

Geographical Terminology…

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Meteorology 101

Temperature

Layering of the

Layering of the Atmosphere

Atmosphere

Altitude Altitude (mi) (mi) 6-8 6-8 Planetary Planetary Boundary Boundary Layer Layer Troposphere Troposphere Stratosphere Stratosphere

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Meteorology 101

Some Fundamentals

•

• Earth is heated unevenly: Tropics are

Earth is heated unevenly: Tropics are

warmer than the Polar Regions.

•

• Nature tries to try to even

Nature tries to try to even

out

temperature differences.

•

• Uneven heating sets atmosphere in

Uneven heating sets atmosphere in

motion and is the fundamental cause

of all weather.

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Meteorology 101

Air Pressure

On average, air weighs

about 14.7 lb/in about 14.7 lb/in22 14.7 lb/in 14.7 lb/in22 _=29.92_=29.92 “inches of mercury” “inches of mercury”

Air Pressure varies over

the globe the globe 1” 1” 1”1” “Top” “Top”

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Meteorology 101

Changing Pressure - Winds

Take more out than put in –

Take more out than put in – decrease pressuredecrease pressure

Put more in than take out –

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Meteorology 101

Changing Pressure - Temperature

Cold

Cold _Warm_Warm

Coldest column = highest pressure **

Warmest column = lowest pressure **

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Meteorology 101

Pressure Differences Create Wind

Air moves from higher toward lower pressure

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Vertical motions also occur

Meteorology 101

Air “converges” at lows, and rises.

Air “diverges” at highs, and sinks.

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Meteorology 101

Actual winds around highs and lows

Reality is more

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Meteorology 101

•

• Lows tend to bring cloudy, wet weather

Lows tend to bring cloudy, wet weather

•

• Highs tend to bring fair, dry weather.

Highs tend to bring fair, dry weather.

Rising

Rising Air

Air near

near

ows

•

• Rising air cools; water vapor in the air

Rising air cools; water vapor in the air

condenses to form clouds/precipitation

Sinking

air

near

ighs

•

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Meteorology 101

Low or lowering pressure = “Lousy” weather

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Meteorology 101

Warm Warm Cold Cold

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Meteorology 101

•

• Temperature

Temperature

differences

concentrated

Front

Front =

=

Battleground of

Air Masses

• Zone of lower

pressure where

lows (storms)

often form

Warm Warm Cold Cold

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Meteorology 101

Cold Front Cold Front

Cold air advances Cold air advances Warmer Warmer Colder Colder Warm Front Warm Front Warm air Warm air advances* advances* Colder Colder Warmer Warmer Stationary Front Stationary Front Warmer Warmer Colder Colder

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Meteorology 101

What happens when air masses meet at What happens when air masses meet at

fronts? fronts?

Cold air lifts the warmer air.

Clouds and precipitation form.

Warm

Cold

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Meteorology 101

Westerlies

Westerlies - High-Altitude winds blow- High-Altitude winds blow

generally west-to-eas

generally west-to-east 3-6 miles t 3-6 miles above mid-above

mid-latitudes.

latitudes.

Jet Stream

Jet Stream – River of fastest-moving air– River of fastest-moving air

within the westerlies.

Ridge

Trough

Upper-Level

Level

Features

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Meteorology 101

Reality is messier …

Still, highs and Lows move with the

westerlies and the jet stream.

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RIDGE RIDGE

Highs and Lows form and dissipate in synch with

ridges and troughs in the westerlies.

Meteorology 101

TROUGH TROUGH SINKING SINKING AIR

AIR RISINGRISING AIR AIR HIGH HIGH PRESSURE PRESSURE FAVORED FAVORED LOW LOW PRESSURE PRESSURE FAVORED FAVORED

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Meteorology 101

Stationary Front separates air masses

COLD

WARM

LOW

This

is

your

life!

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Meteorology 101

Area of low pressure develops along front

COLD

WARM

LOW

This

is

your

life!

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Meteorology 101

Circulation around low sends cold air and

warm air advancing

LOW

This

is

your

life!

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Meteorology 101

Low and fronts move with the upper-air

westerlies while circulating low-level air

COLD

WARM

LOW

This

is

your

life!

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Meteorology 101

Typical cloud and precipitation shield of a

low-pressure system and fronts

Cloud Cloud Shield Shield Precipitation Precipitation Shield Shield Warm Warm Sector Sector

LOW

This

is

your

life!

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Intense lows Intense lows often take on a often take on a “comma-cloud” “comma-cloud” shape when shape when viewed from viewed from space. space.

Meteorology 101

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Land Land Water Water

Meteorology 101

Local Winds

Uneven heating working on a smaller scale

Sea Breeze Sea Breeze Warm Warm Heats Heats faster faster

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Meteorology 101

Another control on vertical motions

Vertical temperature structure of the

atmosphere

Inhibits Overturning

Pillows

Pillows (Light)(Light)

Books

Books (Heavy)(Heavy) _Pillows_{Pillows (Light)}_(Light)

Books

Books (Heavy)(Heavy)

More likely More likely to overturn to overturn STABLE STABLE

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Meteorology 101

• Typically, temperature decreases with

altitude, so the lighter stuff (warmer air) is

below the heavier stuff (colder air).

In the Atmosphere…

• Typically supports some overturning,

especially in the boundary layer.

Cumulus

clouds

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Meteorology 101

“STABLE”

Warmer Warmer Colder Colder Light stuff Light stuff Heavy Stuff Heavy Stuff Temperature Temperature Inversion –

Inversion – A layer of the atmosphere inA layer of the atmosphere in

which temperature increases with height.

Inversion

But Sometimes …

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Meteorology 101

Inversions inhibit vertical mixing. Inversions inhibit vertical mixing. Can trap pollutants in

Can trap pollutants in the lower atmosphere.the lower atmosphere.

Air sinks and

warms near warms near high pressure. high pressure. Temperature Temperature Creates an Creates an inversion 1000s inversion 1000s of feet above of feet above the ground. the ground.

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Meteorology 101

Inversions inhibit vertical mixing. Inversions inhibit vertical mixing. Can trap pollutants in

Can trap pollutants in the lower atmosphere.the lower atmosphere.

Warmer Warmer Colder Colder

Colder, heavier air

trapped in valleys.

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Meteorology 101

•

• Wind and rising air Wind and rising air disperse pollutants.disperse pollutants.

Key Ideas

•

• When air rises, When air rises, clouds/precipitaclouds/precipitation can form.tion can form.

•

• Clouds reduce sunlight, which slows Clouds reduce sunlight, which slows productionproduction

of some pollutants; precipitation cleanses the air.

•

• Air rises, and winds Air rises, and winds are strongest, in theare strongest, in the

vicinity of low pressure and fronts.

• Air sinks, and winds tend to be light, in the

vicinity of high pressure.

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Weather Forecasting

•

• Observations, observations, observationsObservations, observations, observations

(surface, upper-air, satellite, radar, etc)

•

• KnowledgeKnowledge of how atmosphere worksof how atmosphere works

(e.g., high and low

(e.g., high and low pressure, fronts, etc)pressure, fronts, etc)

•

• Computer guidanceComputer guidance (the “models”)(the “models”) •

• Personal experiencePersonal experience (“I’ve seen that before”)(“I’ve seen that before”)

Meteorology 101

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Surface

observations

Meteorology 101

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Meteorology 101

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Sources of Surface Observations Sources of Surface Observations

•

• ASOSASOS – Owned and maintained by the NWS– Owned and maintained by the NWS

• Federal

• Federal AWOSAWOS – Owned and maintained by the FAA– Owned and maintained by the FAA

• Non-Federal

• Non-Federal AWOSAWOS – Owned and maintained by state, city,– Owned and maintained by state, city,

and county agencies (incl. DOT), and private airports

•

• Military bases – manually taken Military bases – manually taken observationsobservations

•

• CoOp observers – NWS volunteer network, manually takenCoOp observers – NWS volunteer network, manually taken

observations

*All are transmitted via FAA data lines to

*All are transmitted via FAA data lines to NWS to WSI toNWS to WSI to

TWC.

ASOS

ASOS – Automated Surface Observing System– Automated Surface Observing System

AWOS

AWOS – Automated Weather Observing Station– Automated Weather Observing Station

Meteorology 101

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Other Sources of Surface Observations Other Sources of Surface Observations

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• Private Mesonets – such as AWS (Weatherbug), etc.,Private Mesonets – such as AWS (Weatherbug), etc.,

•

• Owned and operated by private networkOwned and operated by private network

• Not available for use by other private companies

Meteorology 101

• Public Mesonets – including RWIS,

• Public Mesonets – including RWIS, etc.etc.

•

• Owned and operated by Owned and operated by government agenciesgovernment agencies

•

• May not be centrally collectedMay not be centrally collected

•

• Academic/Research MesonetsAcademic/Research Mesonets

•

• Owned and operated by universities and researchOwned and operated by universities and research

institutions

• May be available for use by

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Upper-air

observations

Meteorology 101

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Satellite Satellite Imagery Imagery 1 km resolution 1 km resolution

Meteorology 101

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Visible

Visible WaterWater_Vapor_Vapor

Meteorology 101

Infrared

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Doppler Doppler Radar Radar

Meteorology 101

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Tornado on Doppler Radar

R

Reefflleeccttiivviittyy VVeelloocciittyy

Meteorology 101

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Doppler radar network

Meteorology 101

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Weather forecasts have improved

Meteorology 101

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Meteorology 101

Computer Models:

Numerical Weather Prediction

Temp Temp future future time time

=

Temp Temp now now

+

Change in Temp Change in Temp between now between now

and future time

What processes change temperature?

• • SunshineSunshine • Wind Direction • Wind Direction • Evaporation • Evaporation • Pressure changes • Pressure changes

• Etc, etc, etc

Computer is programmed Computer is programmed with mathematical with mathematical representations of these representations of these processes. processes.

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ENIAC - University of Pennsylvania, 1945

Meteorology 101

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Meteorology 101

Modern Computer Model Output (map form)

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Meteorology 101

Modern Computer Model Output (map form)

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Meteorology 101

FOUS62 KWNO 171200 FOUS62 KWNO 171200

OUTPUT FROM ETA 12Z FEB 17 04 OUTPUT FROM ETA 12Z FEB 17 04

TTPTTR1R2R3 VVVLI PSDDFF HHT1T3T5 TTPTTR1R2R3 VVVLI PSDDFF HHT1T3T5 TTPTTR1R2R3 VVVLI PSDDFF HHT1T3T5 TTPTTR1R2R3 VVVLI PSDDFF HHT1T3T5 DCA//504026 02523 370707 34989496 ORF//766649 -1014 340515 40039999 DCA//504026 02523 370707 34989496 ORF//766649 -1014 340515 40039999 06000527423 01319 331007 34019596 06007938417 02008 310314 41030000 06000527423 01319 331007 34019596 06007938417 02008 310314 41030000 12000736828 -0615 300709 34019696 12015968326 -1805 270120 41030000 12000736828 -0615 300709 34019696 12015968326 -1805 270120 41030000 18000885821 -0814 280212 32009696 18001968328 -6009 253518 39020000 18000885821 -0814 280212 32009696 18001968328 -6009 253518 39020000 24000925418 -1114 263614 30989795 24000966327 01213 233422 34019897 24000925418 -1114 263614 30989795 24000966327 01213 233422 34019897 30000562608 -3115 243414 30039794 30000784707 -1612 233521 32029796 30000562608 -3115 243414 30039794 30000784707 -1612 233521 32029796 36000552244 -1619 233316 35019795 36000602016 -2418 223314 35049895 36000552244 -1619 233316 35019795 36000602016 -2418 223314 35049895 42000644246 -1316 192811 38000098 42000602335 00618 203113 40029999 42000644246 -1316 192811 38000098 42000602335 00618 203113 40029999 48000485637 06212 152415 41010099 48000534040 -2716 182620 43020399 48000485637 06212 152415 41010099 48000534040 -2716 182620 43020399

Modern Computer Model Output (tabular form)

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Some “folklores” are useful

Meteorology 101

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Meteorology 101

Fundamentals

of Weather

Jon Nese and Jen Carfagno

The Weather Channel

February 22, 2004

(Some)

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•

• WhatWhat valuevalue can we add (eg, experts).can we add (eg, experts).

•

• Communication of Communication of uncertaintyuncertainty - the- the

atmosphere is a very

atmosphere is a very complicated systemcomplicated system

(hurricanes, March 2001 snowstorm)

•

• EducateEducate the publicthe public

TWC Mission

Making a difference in people’s

lives, one forecast at a time.

Meteorology 101

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Operations Overview

Meteorology 101

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