Weather Instruments
P 611-620
We need data to _______________ the weather
1.
2.
3.
4.
5.
6.
Instruments used to gather the data
 ___________________________ Atmospheric Conditions
Temperature
 Instrument ____________________________
• Uses a ______________ either mercury or alcohol sealed in a
glass tube
 Electrical thermometer
• As temp ____________the electrical current increases
• A thermistor responds very quickly and is used where temps
change quickly
Air pressure
Instrument ____________________________
 Aneroid
 Mercury
 _______________ are usually indicated by a drop in air pressure
Wind Speed and Direction
 Instrument __________________________
 Wind _____________________
 Instrument Wind vane
 Wind _______________________
Measuring Upper Atmospheric Conditions
Radar
Stands for Ra______________, D________________&
R__________________
 Uses ____________________ radio waves
Doppler radar
 Can indicate precise location, intensity of precip and extent of a
storm
 Shows wind patterns
 _______________ or ______________ from the radar
Radiosonde
 An instrument package that is carried by a heliumfilled _______________________
 _______________ sends info to ground
 Determines direction and speed of high altitude
winds
Skew-T
 Shows a _______________slice of the
atmosphere
 Temperature on right
 Dew point on left
 Air pressure
 Wind speed and direction
Weather _______________________
Can measure
 visible
 Infrared
 Ocean conditions
 temperature and flow of ocean currents and
 height of ocean waves
Computers
 Solve _________________________________ equations that
describe the __________________________ of the atmosphere
 Can store weather _________________
 Can store weather records
This info is reported from _______________________
 WMO World Meteorological Organization
 10,000 land based stations and hundreds of ship-based stations
Weather satellites
 ______________ Global Orbiting Earth Satellite
Data from stations is compiled and analyzed to forecast
 In the past this was done by _______________________
 Now much is done by computer
 But, different programs work better for different ____________ and
types of weather
 Often two or three computer _________________ are consulted to
make one forecast
Weather Station Symbols p616
 ____________________ is upper left corner
 Barometric (_______) pressure is upper _____________________
Air pressure
 represents the last three digits of the observed pressure reading in
_________________________ (mb)
 Like on previous labs
Dew point
 Dew Point is lower ______________corner
 When the air temperature and the dew point are the ___________
the air is _______________________________
 Relative humidity can be ____________________
 High if temp and dp are close
 Low if large difference between dp and temp
Relative Humidity can be ______________________
 When the air and dew point temperatures are very close, this
indicates that the air has a _______________relative humidity.
 The opposite is true when there is a large difference between air and
dew point temperatures, which points to air with a ___________
relative humidity.
Wind Speed and Direction
 Wind barbs point in the direction _____________ which the wind is
blowing
Look at the picture and answer the following questions.
What is the temperature?___________________
What is the dew point?_____________________
What is the air pressure? (careful)____________
Which direction is the wind from? ____________
What is the wind speed? ___________________
What is the percent of cloud cover? __________
Methods of Forecasting
1. Persistence
2. Trend
3. Analog
 Persistence—based on ___________________of a weather
pattern—if it is raining now it will probably be raining tomorrow
 Trend—based on the ___________________ or trend of the
weather system Ex. Cold front moving E at 20 Km/hr will affect
weather 80 KM away in 4 hours
 Analog
Others
 Climatology—data accumulated through many years
th of July is usually hot and dry
 4
 Numerical Weather Prediction—uses programs built by
meteorologists
 Not exact
 compares present weather (cloud cover, wind, temperature,
humidity, etc) with weather conditions produced by same features in
the past
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.
 OU is the best
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
Types of fronts
 Named for the invader
 Each type of front has a typical weather scenario
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.
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.
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
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.
Where are the fronts?
Stationary front
 Change in wind direction
 Can dump heavy rains
Warm Front
 Marked temperature difference
Cold front
 Cold temperatures are moving in
 If it is not exactly on the value it will not
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
The closer contour lines are to one another, the higher the wind
speed.
Where is the wind speed high? Where is it low?
Inside a series of closed contours (the contours make a circle) is a
High or Low pressure
Describe the motion of the wind.
Wind Flow around Isobars
 Winds flow roughly parallel to the isobars, as depicted in the
schematic below

Current Weather Conditions
Current
Weather Station Data
Source:University of Illinois
 http://ww2010.atmos.uiuc.edu/(Gh)/home.rxml