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Weather Instruments P 611-614.

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Presentation on theme: "Weather Instruments P 611-614."— Presentation transcript:

1 Weather Instruments P

2 We need data to forecast the weather
Temperature Air pressure Humidity Type of clouds Level of precipitation Wind direction and speed

3 Instruments used to gather the data
Lower Atmospheric Conditions Temperature Thermometer Uses a liquid either mercury or alcohol sealed in a glass tube Electrical thermometer As temp rises the electrical current increases A thermistor responds very quickly and is used where temps change quickly

4 Air pressure Barometer Aneroid (pictured) Mercury
fronts are usually indicated by a drop in air pressure

5 Wind Speed and direction
Anemometer Wind speed Wind vane Wind direction

6 Rainfall Rain gauge

7 Measuring Upper Atmospheric Conditions

8 Doppler image of a hurricane

9 Radar Doppler radar Stands for radio detection and ranging
Uses reflected radio waves Doppler radar Can indicate precise location, intensity of precip and extent of a storm Shows wind patterns Towards or away from the radar

10 Radiosonde An instrument package that is carried by a helium-filled balloon Radio sends info to ground Determines direction and speed of high altitude winds


12 Skew-T Shows a vertical slice of the atmosphere Temperature on right
Dew point on left Air pressure Wind speed and direction


14 Weather Satellites Can measure visible Infrared Ocean conditions
temperature and flow of ocean currents and height of ocean waves

15 Computers Solve mathematical equations that describe the behavior of the atmosphere Can store weather data Can store weather records

16 This info is reported from stations
WMO World Meteorological Organization 10,000 land based stations and hundreds of ship-based stations Weather satellites GOES Global Orbiting Earth Satellite

17 Data from stations is compiled and analyzed to forecast
In the past this was done by hand Now much is done by computer But, different programs work better for different locations and types of weather Often two or three computer models are consulted to make one forecast

18 Weather Station Symbols
Temperature is upper left corner Barometric (air) pressure is upper right

19 Air pressure represents the last three digits of the observed pressure reading in millibars (mb) Like on previous labs

20 Dew point Dew Point is lower left corner
When the air temperature and the dew point are the same the air is saturated Relative humidity can be inferred High if temp and dp are close Low if large difference between dp and temp

21 Relative Humidity can be inferred
When the air and dew point temperatures are very close, this indicates that the air has a high relative humidity. The opposite is true when there is a large difference between air and dew point temperatures, which points to air with a low relative humidity.

22 Wind Speed and Direction
Wind stick points in the direction "from" which the wind is blowing Which direction is the wind from?

23 Wind Speed May be measured in mph, km/hr or knots
The more barbs the windier it is Each long barb is approx 10 knots


25 Cloud Cover

26 Precipitation Symbols

27 Worksheets Surface Weather Map Study the tables and the station model
Use the info to answer the questions Transparency worksheets

28 Dry Line Note the sharp difference in dew points
The line that separates dry air from moist air

29 Isobars Lines that connect points with equal air pressure
Drawn at 4 mb (millibar) intervals

30 Pressure and Wind Relationships
Draw isobars Use pencil CI = 4 Mark high and low pressure Answer the questions

31 Methods of Forecasting
Persistence Trend Analog

32 Persistence Persistence—based on continuity of a weather pattern—if it is raining now it will probably be raining tomorrow

33 Trend Trend—based on the movement or trend of the weather system Ex. Cold front moving E at 20 Km/hr will affect weather 80 KM away in 4 hours

34 Happy Birthday, Hoang

35 Analog compares present weather (cloud cover, wind, temperature, humidity, etc) with weather conditions produced by same features in the past Others Climatology—data accumulated through many years 4th of July is usually hot and dry Numerical Weather Prediction—uses programs built by meteorologists Not exact

36 Meteorologists What high school courses are necessary to prepare for a career in meteorology? Because meteorology is a science, a good background in mathematics and the sciences is mandatory. Knowledge of physics and chemistry is helpful toward a career in the atmospheric sciences.

37 OU is the Best for Meteorology

38 Weather Station Symbols
Temperature is upper left corner Barometric (air) pressure is upper right

39 Lab Do isotherms in red (every 2) Do isobars in blue (Every4)
Do lightly in pencil first Do isobars in blue (Every4)

40 Winds

41 Three causes of motion(recap)
WIND ALWAYS FLOWS FROM HIGH TO LOW PRESSURE 1. Warm air rises and cool air sinks because of density This is called a convection current 2.pressure differences in the atmosphere that are a result of temperature differences Wind is horizontal air movement 3. The deflection of objects to the right in the northern hemisphere—called the Coriolis Effect Due to rotation of the earth

42 Winds blow from high to low pressure.

43 Highs and Lows? Winds circle Clockwise around a high
Highs generally mean cold dry air that is sinking High pressure usually = fair weather

44 Low Pressure Systems Winds circle counterclockwise around a low
Warmer air rises and cools and forms clouds and precipitation Low pressure usually = rainy weather

45 Global Circulation Patterns
We are located in the Westerlies section That means our weather moves from the west coast to the east coast

46 Overall movement is west to east
Local wind patterns can be from any direction

47 Recognizing fronts on a map
sharp temperature changes over relatively short distances changes in the moisture content of the air (dew point) shifts in wind direction low pressure troughs and pressure changes clouds and precipitation patterns

48 Types of fronts Named for the invader
Each type of front has a typical weather scenario

49 Cold Front heavy cold air displaces lighter warm air, pushing it upward Cumulus clouds form and usually grow into thunderstorms Temperatures drop anywhere from 5 to 15. Winds become gusty and erratic. Rain, snow, sleet, and hail can occur with a cold front.

50 Warm Front Warm fronts occur when warm air replaces cold air by sliding over it. Altocumulus clouds form and may be associated with rain, snow, or sleet. Temperatures may warm slightly. Winds are usually gentle with this kind of front.

51 Stationary Front neither warm nor cold air advances. The two air masses reach a stalemate. That is what stationary means - that neither front is moving. can last for days, producing nothing but Altocumulus clouds Temperatures remain stagnant and winds are gentle to nil

52 Occluded Front cold air is replacing cool air or vice versa at the surface, with warm air above. Both types of fronts are usually associated with rain or snow and cumulus clouds. Temperature fluctuations are small and winds are gentle.

53 Where are the fronts? Stationary front Change in wind direction
Can dump heavy rains

54 Warm Front Marked temperature difference

55 Cold front Cold temperatures are moving in

56 Wind and Pressure Relationship Lab

57 Remember Topographic Maps?

58 Same Concept—Different Use
Isotherm=equal temperature Isobar=equal barometric pressure

59 contour interval (CI) The contour intervals vary
Isobars often have an interval of 4 Read the directions or look at examples to see the contour level

60 Iso therm Equal temperature
If a station reports the exact value the line will go through the station symbol If it is not exactly on the value it will not

61 Points shown are reporting stations
Here, the stations reported pressure and temperature The lines are drawn in different colors to help differentiate them There may be areas that do not report or have no station

62 The closer contour lines are to one another, the higher the wind speed.

63 Where is the wind speed high? Where is it low?

64 Inside a series of closed contours (the contours make a circle) is a High or Low pressure

65 Describe the motion of the wind.

66 Wind Flow around Isobars
Winds flow roughly parallel to the isobars, as depicted in the schematic below


68 Current Weather Conditions

69 Current Weather Station Data

70 Source:University of Illinois

71 Metars In a small group try to figure out what each set of numbers or letter mean TYPEIDTIMEWINDVISWXSKYT/TDALTREMARKMETAR KORD Z 19020G26KT 6SM -SHRA BKN070 12/08 A3016 RMK AO2

72 Understanding Metars Activity
Brainstorm about what the numbers and letters may mean Discuss as a class Interpret metars and decode them

73 Zulu Time Used to be known as Greenwich Mean Time
Uses the military clock of 24 hours For numbers above 13 subtract 12 Converting to KS time For CST –6 For CDT -5

74 Upper Air Data Shows

75 Become a meteorologist
OU is the best


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