Thermometer

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Thermometer

• Variable temperature
• Units Degrees Celsius (oC)
• Accuracy marked to 0.5 oC
• Cost 10
• Site in the shade (e.g. a Stevenson Screen)
• Mercury (or sometimes coloured alcohol) in the
  bulb expands and contracts up the calibrated tube
  with changes in the ambient air temperature

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Max Min Thermometer

• Details as for thermometer, except an index
  marker is pushed up or down by the tube of
  mercury to indicate the maximum or minimum

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Whirling hygrometer

• Variables temperature and wet bulb temperature
• Units Kelvin or Degrees Celsius
• Accuracy marked to 0.5 oC (range -5 to 50 oC)
• Cost 45
• Site in the shade
• Whirl it round your head so the thermometer bulbs
  are well ventilated and there is sufficient
  evaporation from the wet bulb to achieve lowest
  possible temperature.

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Assman psychrometer

• Similar to the whirling hygrometer, but uses a
  wind up fan to ventilated the dry and wet bulb
  thermometers.

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Humidity slide rule

• Variable converts between water vapour content
  measures
• Units n/a
• Accuracy 1
• Cost cheap!
• Site n/a
• A ready-reckoner for conversion between, e.g. wet
  bulb temperature and relative humidity

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Barograph (recording Barometer)

• Variable atmospheric pressure
• Units millibars (mb) or Pascals (Pa)
• Accuracy 0.1 mb
• Cost ?
• Site Anywhere
• An aneroid barometer contains a partial vacuum in
  the sealed metal aneroid cell, hence changes in
  pressure are amplified by movements of the arm
  attached to the cell.

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Net radiometer

• Variables upwelling and downwelling radiation
• Units W m-2
• Accuracy ?
• Cost ?
• Site Exposed site without shading
• Dark surfaces absorb longwave or shortwave
  radiation, causing a change in voltage which can
  be measured electronically and converted to
  radiation.

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Dome solarimeter

• Variable solar radiation
• Units W m-2
• Accuracy ?
• Cost ?
• Site exposed
• As for net radiometers

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Tipping bucket raingauge

• Variable rain rate and amount
• Units mm
• Accuracy 0.2 mm
• Cost 300-700
• Site exposed horizontal location
• Rain falls into cone and tips a small bucket once
  full, with that time recorded, thus a rain rate
  can be observed. Cone amplifies signal.

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Air meter

• Variable the run of air hence wind speed
• Units m m s-1
• Accuracy dependent on the observation time
• Cost no longer available.
• Site away from buildings, etc
• Impeller spun round by the wind, turning dials to
  measure the wind run.

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Handheld anenometer

• Variable wind speed (instantaneous)
• Units m s-1 or equivalent
• Accuracy poor.
• Cost cheap
• Site handheld
• Wind blows the cups around to give an
  instantaneous reading.

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Sodar (Acoustic Radar)

• Variable Backscatter
• Units amplitude
• Accuracy ?
• Site away from buildings, people, noise!
• Cost 1000-10,000
• Acoustic pulses are scattered back to the
  receiver, from small-scale density changes (e.g.
  turbulence), with the volume and time-lag
  measured to give amplitude and range.

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Sodar (Acoustic Radar)

• Variable Backscatter
• Units amplitude
• Accuracy ?
• Site away from buildings, people, noise!
• Cost 1000-10,000
• Acoustic pulses are scattered back to the
  receiver, from small-scale density changes (e.g.
  turbulence), with the volume and time-lag
  measured to give amplitude and range.

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Doppler sodar

• Variable Backscatter derived wind profiles
• Units n/a and m/s
• Accuracy 1 m/s
• Site remote!
• Cost 10,000
• Acoustic beams fired in several directions, so
  scatters relative movement can be determined, and
  hence wind speed direction in 3D.

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Doppler sodar

• Variable Backscatter derived wind profiles
• Units n/a and m/s
• Accuracy 1 m/s
• Site remote!
• Cost 10,000
• Acoustic beams fired in several directions, so
  scatters relative movement can be determined, and
  hence wind speed direction in 3D.

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Radiosonde (Upper air sounding)

• Variables an atmospheric sounding (i.e.
  vertical profile) of, typically, pressure,
  temperature, relative humidity wind
• Units various
• Accuracy various
• Cost 100 per sonde
• Site away from buildings, good spatial
  representation, often airports
• Balloon is filled with Helium gas and released
  rising up few metres per second, the radiosonde
  measures and transmits data to a ground station

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Radiosonde (Upper air sounding)

• Variables an atmospheric sounding (i.e.
  vertical profile) of, typically, pressure,
  temperature, relative humidity wind
• Units various
• Accuracy various
• Cost 100 per sonde
• Site away from buildings, good spatial
  representation, often airports
• Balloon is filled with Helium gas and released
  rising up few metres per second, the radiosonde
  measures and transmits data to a ground station

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Radar

• Variables Backscatter, usually from
  hydrometeors, such as rain drops, hail, snow,
  etc.
• Units backscatter amplitude
• Accuracy ?
• Site away from buildings, good spatial
  distribution
• Cost 10,000-1millions
• Radio waves emitted and reflected back, with
  return amplitude and time-lag giving backscatter
  intensity and range. These can be related to
  precipitation intensity.
• Doppler radars also available.

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Radar

• Variables Backscatter, usually from
  hydrometeors, such as rain drops, hail, snow,
  etc.
• Units backscatter amplitude
• Accuracy ?
• Site away from buildings, good spatial
  distribution
• Cost 10,000-1millions
• Radio waves emitted and reflected back, with
  return amplitude and time-lag giving backscatter
  intensity and range. These can be related to
  precipitation intensity.
• Doppler radars also available.

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Radar

• Variables Backscatter, usually from
  hydrometeors, such as rain drops, hail, snow,
  etc.
• Units backscatter amplitude
• Accuracy ?
• Site away from buildings, good spatial
  distribution
• Cost 10,000-1millions
• Radio waves emitted and reflected back, with
  return amplitude and time-lag giving backscatter
  intensity and range. These can be related to
  precipitation intensity.
• Doppler radars also available.

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Satellites!

• Variable Radiation derived brightness
  temperature
• Units W derived K
• Resolution down to lt 1 km
• Site space! Either geostationary or polar orbits
• Cost millions millions
• Passive satellites measure up-welling radiation
  at various wavelengths (visible, infra red
  microwave)
• Active satellites work more like radars.

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Satellites!

• Variable Radiation derived brightness
  temperature
• Units W derived K
• Resolution down to lt 1 km
• Site space! Either geostationary or polar orbits
• Cost millions millions
• Passive satellites measure up-welling radiation
  at various wavelengths (visible, infra red
  microwave)
• Active satellites work more like radars.

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Satellites!

• Variable Radiation derived brightness
  temperature
• Units W derived K
• Resolution down to lt 1 km
• Site space! Either geostationary or polar orbits
• Cost millions millions
• Passive satellites measure up-welling radiation
  at various wavelengths (visible, infra red
  microwave)
• Active satellites work more like radars.

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Observing scenarios

• You have been tasked with determining the
  structure governing physics of the wind field
  over Greenland discuss in groups how to achieve
  this challenge.