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Temperature and Ground

Hog day

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Ground Hog Day• Ground Hog Day - if the ground hog sees his shadow

there will be 6 more weeks of winter.

• German superstition used animals to predict weather. Germany used a hedgehog.

• Pennsylvania - German settlements - 1887 - first ground hog named Phil. Today is the 5th generation in Pennsylvania - 7:00 a.m. Penn. Time in Globber Hill -Ground Hog Club. A very big tradition - people dress up and many tourists come to see the festival. Ground Hogs usually hibernate. They are woken up for the tradition. Phil is about 14 pounds.

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Proclaimation being read for ground hog day at Globber Nob

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Punxsutawney Phil making his annoucement!

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Feb 2, 2013

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•Atmospheric Properties that describe weather conditions

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Temperature vs. Heat•   

• Temperature vs. Heat - Temperature measures how rapidly or slowly molecules move around.

 • Heat is the transfer of energy because of difference of

temperature between substances.• Temperature Scales:

•  •  •  •  •  

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Causes of weather• Meteorology – study of atmospheric phenomena Greek meaning of Meteors – high in the airTypes of atmospheric meteors Clouds, raindrops, snow flakes, fog, dust, rainbows

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Cloud droplets - hydrometers• Lithometeors- smoke, haze, dust• Electrometeors- thunder, lightning

• Weather – current state of atmosphere.• Climate – long term variation – determine over 30

years span or more.

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Tropics• Temperature is constant there. Why? • Through constant motion of air and water

relocation• Air masses – large body of air that takes on the

characteristics of the area in which it formed (Source Region).

• Land Air masses – less moisture• Water Air Masses – more moisture ( high evap.)

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Classification of Air Masses• According to source region• (CT) Continental Tropical –warm and dry• (MT) Martime Tropical – warm and humid• (CP) Continental polar – cold and dry• (MP) Maritime polar – cold and humid• ( A) Arctic – Much colder – same as continental

polar air masses associated with very high pressure.

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Source Region• 5 main types of air masses in the U.S. – due to the

continents location to the source regions associated with each air mass.

• Maritime polar (California) –Forms over the North Atlantic and North Pacific.

• This is why we have heavy rains in the winter.

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Source Regions cont……• Continental Polar- freezes the middle /Northern

part of the U.S. Forms over the interior of Canada and Alaska.

Maritime Tropical Air – forms in tropical and subtropical oceans ( Caribbean Sea and Gulf of Mexico)

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Source Region cont….• Maritime Tropical Air- forms in the Western U.S. Summer brings hot humid weather to the eastern 2/3 of the U.S. and Canada.• Continental Tropical Air – Desert Southwest and

Mexico and source region , Hot/Dry• Arctic- Develops over latitudes of 60 N Ice Regions of Siberia and Arctic Basin

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Air Mass Modification• As air masses move over the surface of the earth,

they acquire the characteristics of other source regions, In time loses it’s identity.

• Weather systems- earth rotates around the sun ,• The rotations causes the Coriolis Effect. • S, Hemisphere: deflect to left• N Hemisphere : deflect to right

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Hadley Cell• This cell creates a belt of high pressure. • It causes weak surface winds. • Called Horse Latitude

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ITCZ• Inter Tropical Convergence Zone Air converges and is formed upward. Area of low pressure forms over a large area. Low pressure migrates wit movement of the sun’s rays.

Weather is normally cloudy with showers. Great for the tropical rain forest.

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Trade Winds• Between 30 * N and 30* S • Air sinks, warms and moves back toward 30* and

sinks again ( warm air rises, cold air sinks). Example of a Convection cell.

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Prevailing Westerlies• Located between 30* and 60* • They move opposite of Trade winds. The winds blow towards the poles in an easterly direction( blows for west to east) Responsible for the weather for the U.S.

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Polar Easterlies• Lies 60 * N and 60* S • Characterized by cold air.

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Jet Streams• Narrow band of fast, high altitude westerly winds • Speed are up to 185 km/hr 2 Jet Streams Polar Jet – separates Easterlies from prevailing westerlies. Subtropical Jet Stream-Where trade winds meet prevailing westerlies.

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Jet Streams

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Cold Front• Cold dense air replaces warm air forcing it

upward. ‘• Warm air condenses as cooling• Clouds, showers and thunderstorms associated• The Front moves fast so a steep front develop• The points on the symbol indicates the directional

movement.

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Cold Front Symbol

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Warm Front• Warm air displaces the cold air • Warm front is a gradual slope due to the air in

front moving slower.• The warm front encounters less frictionWeather is extensive cloudiness and precipitation. Points on the symbol point in the directional movement.

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Warm Front symbol

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Stationary Front• The meeting of two air masses and neither is

moving in a direction.• Occurs due to modifications that have occurred

there is little imbalances.• Weather patterns are similar to a warm front.

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Occluded Front • Cloud air mass moves so rapidly it overtakes a

warm front• Cold air mass wedge pushes the warm air

upwards.

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Occluded Front

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Summary of Front Symbols

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Pressure Systems• Rising air associated with low pressure• Sinking air associated with high pressureWeather is basically rotating High and low pressure produced by rising and sinking air combined with the Coriolis effect

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Rotation of Pressure

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High Pressure• Air sinks• The air reaches the surface and spreads out• Air is deflected to the right or clockwise in the

Northern Hemisphere. It rotates to the counter clockwise in the Southern Hemisphere.

• Associated with cold air masses, fair weather• Found in subtropical oceans

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High Pressure

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Low Pressure• Air rises and is replaced by air from outside the

system so it flows toward the center.• Weather is cloudy and precipitation• Found in the middle latitudes• Wave cyclone begins along a stationary frontImbalances occur and pushes the front south and another part north.Weather produced affects large areas.

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• Saturation - point at which air holds as much H 2O vapor as possible. Condensation cannot happen until saturation is reached.

•  • H2O vapor changes to liquid (rain)

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Saturation of Air

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Vertical Temperature Changes• As air masses rise over, mountains tend to cool.

Remember clouds are suspended H2O vapor. As cloud rises, temperature cool then condensation temperature reach LCL (lifted condensation level) base level of clouds. Above LCL air becomes saturated and cools more slowly. The rate that saturated air cools is called the moist adiabatic lapse rate.

• Range - 4°C/1000m to 9°C/1000m• (warm air) (cold air)

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Meteorologist measure atmospheric variables:

• temperature; air pressure; wind; relative humidity to make accurate weather forecasts

 • The two most important factors of weather

forecasting are: accuracy and density of data

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Instruments• Thermometers - measures temperature - heights of

liquid column indicates temperature from the expansion of the liquid. There are two types: mercury and alcohol.

• Barometer - measures air pressure. There are two types:

• mercury barometer - air pressure changes with the height of the mercury.

• aneroid barometer - metal container with a vacuum chamber inside. This chamber contracts or expands with changes in air pressure.

 

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Mercury Barometer

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Aneroid Barometer

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Hydrometer- measures relative humidity

 

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Ceilometer - measures the height of the cloud layers. It also estimates the amount of cloud cover.

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ASOS - Automated surface observing system - gathering data in 1700 areas at regular intervals

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Accurate forecasting requires atmospheric data at height of 3000m

 • Radioscope - measures upper level data - temperature,

pressure, and humidity.•  • Doppler Radar - measures wave frequency that occurs in

energy such as sound and Light Data is plotted - indicates wind speed and the movement of the front.

•  • Weather satellites - takes a picture of earth at regular

intervals•  • Infrared Imagery - used to measure surface temperature

difference. * Detects strong thunderstorms.•  

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Doppler Radar - measures wave frequency that occurs in energy such as sound and Light Data is plotted - indicates wind speed and the movement of the front.

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Weather satellites - takes a picture of earth at regular intervals

 

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Infrared Imagery - used to measure surface temperature difference. * Detects strong thunderstorms.

 

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Weather AnalysisStation Model - Record of weather data for a particular site• Allow meteorologists to fit a large amount of date

into a small space • Provides a uniform way of communicating: 

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Plotting data Across a piece of land• Isopleths - lines connecting points of equal or

constant values • Isobars - lines of equal pressure • Isotherms - line of equal temperature

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Isopleths

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Isobars

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Isotherms

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• Barometric - Pressure • 78 78• 90 60• 50  90 90 88 90 88• 88• 78 50 78 55•  •  • Isobars are close together - strong winds• Isobars are far apart - calm winds•  • Reliable forecast must rely on analyzed date from different levels of the atmosphere•  • Digital forecast - Forecasts that are ones that rely on numerical data. Highly • Dependent on the density of data - main method used•  • Analog forecast - comparing current weather patterns to the past. Used for monthly and

seasonal forecasts•  •  

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Digital Forecast

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Analog Forecasting