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NATS 101

Lecture 3Climate and Weather

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Climate and Weather

“Climate is what you expect.

Weather is what you get.”-Robert A. Heinlein

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WeatherWeather – The state of

the atmosphere:

for a specific place

at a particular time

Weather Elements

1) Temperature

2) Pressure

3) Humidity

4) Wind

5) Visibility

6) Clouds

7) Significant Weather

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Surface Station Model

Temperatures

Plotted F in U.S.

Sea Level Pressure

Leading 10 or 9 is not plotted

Examples:

1013.8 plotted as 138

998.7 plotted as 987

1036.0 plotted as 360Ahrens, p 431

Responsible for boxed parameters

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Sky Cover and Weather Symbols

Ahrens, p 431

Ahrens, p 431

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Wind Barbs

Direction

Wind is going towards

WesterlyWesterly from the West

Speed (accumulated)

Each flag is 50 knots

Each full barb is 10 knots

Each half barb is 5 knotsAhrens, p 432

65 kts from west

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temperature dew point

SLP pressure

wind

cloud cover

Ohio State website

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Practice Surface Station

Temperate (oF)Pressure (mb) Last

Three Digits (tens, ones, tenths)

Dew Point (later) Moisture

Wind Barb Direction and Speed

Cloud Cover Tenths total coverage

Ahrens, p 431

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Decimal point

What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?

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Practice Surface Station

Sea Level Pressure

Leading 10 or 9 is not plotted

Examples:

1013.8 plotted as 138

998.7 plotted as 987

1036.0 plotted as 360Ahrens, p 431

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998

Decimal point

What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?

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Surface Map Symbols

• Fronts

Mark the boundary between different air masses…later

Significant weather occurs near fronts

Current US MapAhrens, p 432

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Upper-Air Model

Conditions at specific pressure level

• Wind • Temperature (C)• Moisture (Later)• Height above MSL• UA 500mb AnalysisAhrens, p 427Ahrens, p 431

Responsible for boxed parameters

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Climate

Climate - Average weather and range of weather, computed over many years.

Whole year (mean annual precipitation for Tucson, 1970-present)

Season (Winter: Dec-Jan-Feb)

Month (January rainfall in Tucson)

Date (Average, record high and low temperatures for Jan 1 in Tucson)

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Climate of TucsonMonthly Averages

Individual months can show significant deviations from long-term, monthly means.

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Average and Record MAX and MIN

Temperatures for Date

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Climate of TucsonProbability of Rain

Cool Site: Western Region Climate Center

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Climate of TucsonExtreme Rainfall

Cool Site: Western Region Climate Center

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Climate of TucsonSnow!

Cool Site: Western Region Climate Center

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Summary

• Weather - atmospheric conditions at specific time and place

Weather Maps Instantaneous Values

• Climate - average weather and the range of extremes compiled over many years

Statistical Quantities Expected Values

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Reading Assignment

• Ahrens

Pages 25-30

Problems 2.1-2.4

(2.1 Chapter 2, Problem 1)

• Don’t Forgot the 4”x 6” Index Cards… I’m getting antsy for a pop quiz. You must be lusting for one too!