Weather Maps and Intro to Climate

7/30/2019 Weather Maps and Intro to Climate

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Weather Map


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Where do you expect to see rainy

weather?


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Isotherms

What is an isotherm?

Isotherms are lines of constant or equal temperature. They are often used on weather maps bymeteorologists to give a large scale view of temperatures across the U.S. If you have ever looked at a weathermap in a newspaper, the isotherms are used to divide the color-filled temperatures. For example, in themap below, temperatures in the 60s may be represented by a yellow color, while temperatures in the 70smay be represented by an orange color. The line that divides the yellow from the orange is the isotherm. Allof the locations between the 60 degree isotherm and the 70 degree isotherm will have a temperaturebetween 60 and 70 degrees.


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Activity 1


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Isobars

Isobars are lines of constant or equal pressure on a weather map. They can be used to find areas of low or highpressure over a broad area (like the U.S.), and they can tell us how intense the system may be. The lines circlingthem are isobars. Generally the lowest pressure is where precipitation is most likely to fall, and high pressures areusually associated with clear and sunny conditions. Where the isobars are close together, windy conditions maybe expected. Elongated areas of low pressure on surface and upper air weather maps are called "troughs" andelongated areas of high pressure are called "ridges."


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Activity 2


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Activity 2


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Surface Station Maps


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Station Weather SymbolsStation Weather Plot Satellite images, fronts, isobars, highs and

lows show large scale weather featuresand help us see the big weather picture.However, meteorologists need to look

closer at the weather data with moredetail. One common way is with station weather

plots. The station weather plot shows thecurrent weather conditions, cloud cover,

wind speed, wind direction, visibility,temperature, dew point temperature,

atmospheric pressure, and the change inpressure over the last three hours. Here is an example of a surface station

weather plot (in black) with labelsexplaining the data (in blue).


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Cloud Cover

The amount that the circle at the center of the stationplot is filled in represents the approximate amount of

total cloud cover. In above case, the sky cover is overcst.Below are the common sky cover depictions.

Clear Scatterd

(25%)

Partly Cloudy

(50%)

Mostly Cloudy

(75%)

Overcast Sky Obscured Data Missing


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Winds

Wind: The longer line, extending from the sky cover plot, points in the direction that

the wind is blowing FROM. The shorter lines, calledbarbs, on the outer end ofthe direction line indicate the wind speed in knots (kt). Each long barbrepresents 10 kt with short barbs (half-lines) representing 5 kt, and each flagrepresents 50kt. In above case, the wind is blowing FROM the northeast andthe wind speed is 25 knots. Below are some more examples of wind plots.

Calm winds 5 knots 15 knots 20 knots 35 knots 65 knots


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Air Pressure Pressure & Pressure Trend: See-level pressure is plotted to the nearest tenths of millibars(mb),

with leading 9 or 10 omitted. For example:- if the pressure was plotted as 028, the complete sea-level pressure

value is 1002.8 mb;- if the pressure was plotted as 462, it would be 1046.2 mb;- if the pressure was plotted as 867, it would be 986.7 mb.

When trying to determind whether to add a 9 or 10 use the numberthat will give you a value CLOSEST to 1000 mb

The pressure trend has two components, a number and symbol, toindicate how much (in tenths of millibars) in the past 3 hoursand thetrend in the change of the pressure during the same period. In abovecase, the pressure was falling after steady or slightly rising andbecoming 3 mb LOWER than it was three hours ago. Below are themeanings of the pressure trend symbols.


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Air Pressure Symbols

Steady Rising, then

steady

Falling, then

steady

Continuously

Rising

Rising after

slightly falling

Rising, then

slowly falling

Continuously

Falling

Falling after

slightly rising

Falling, then

slowly rising


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Surface Condition SymbolsGeneral

Smoke Lightning Rain Shower

Haze Funnel Cloud Snow Shower

Dust Mist Hail

Blowing Snow Heavy Fog Thunderstorm


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Identify five factorsthat affect climate

and explainhow each

affects climate.


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How does latitude

affect climate?

As latitude ________, the averageannual temperature _________.

0 Latitude 90

Tem

perature

decreasesincreases


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How does closeness to a large

body of water affect climate?

Water __________ the temperature._______ summers. _______ winters.

City B is closer to a largebody of water.

Its temperature line is

flatter (moderated).

moderates

Cities A & B are locatedat the same latitude.

Coole

r

Warmer


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The windward sides of theAdirondacks & Catskillsreceive a great deal more

precipitation

The leewardsides of the

Adirondacks &Catskills

receive muchless

precipitation


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How does the

presence of mountainsaffect climate?

Windward Side: ___________Leeward Side: _____________

cool, moist

warm, dry


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Page 14 of the ESRTs

We live in the troposphere.Temperature decreases

with elevation.


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During summer, temperature is strongly controlled by elevation -- cold at the

higher reaches of the Alaska and Brooks Ranges, and warmer in the lowlands.


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How does elevation

affect climate?

As elevation _________, the average

annual temperature __________.

Elevation

Temp

erature

increases

decreases


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How do ocean currents

affect climate?

Warm Currents: warmer climateCold Currents: cooler climate

Weather Maps and Intro to Climate

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