NATS 101

Lecture 3Climate and Weather

Climate and Weather

“Climate is what you expect.

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

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

Surface Station ModelTemperaturesPlotted F in U.S.Sea Level PressureLeading 10 or 9 is

not plotted Examples:1013.8 plotted as 138998.7 plotted as 9871036.0 plotted as 360Ahrens, p 431

Responsible for boxed parameters

Sky Cover and Weather Symbols

Ahrens, p 431

Ahrens, p 431

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 knots

Ahrens, p 432

65 kts from west

temperature dew point

SLP pressure

wind

cloud cover

Ohio State website

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

72

58

111

Decimal point

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

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

42

18

998

Decimal point

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

Surface Map Symbols

• Fronts

Mark the boundary between different air masses…later

Significant weather occurs near fronts

Current US MapAhrens, p 432

Radiosonde

Weather balloons, or radiosondes, sample atmospheric to 10 mb.

They measuretemperature moisture

pressure

They are tracked to get winds

Ahrens, Fig. 1

Radiosonde Distribution

Radiosondes released at 0000 and at 1200 GMT for a global network of stations.

Large gaps in network over oceans and in less affluent nations.

Stations ~400 km apart over North America

Radiosonde for TucsonExample of data taken by

weather balloon released over Tucson

Temperature (red)

Moisture (green)

Winds (white)

Note variations of all fields with height

UA Tucson 1200 RAOB

troposphere

stratosphere

tropopause

temperature profile

moisture profile

wind profile

ClimateClimate - 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)

Climate of TucsonMonthly Averages

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

Average and Record MAX and MIN

Temperatures for Date

Climate of TucsonProbability of Last Freeze

Cool Site: Western Region Climate Center

Climate of TucsonProbability of Rain

Cool Site: Western Region Climate Center

Climate of TucsonExtreme Rainfall

Cool Site: Western Region Climate Center

Climate of TucsonSnow!

Cool Site: Western Region Climate Center

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

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…