atmospheric variables 9/3/2015. air temperature instrument used to measure: instrument used to...
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Atmospheric Atmospheric VariablesVariables
04/19/2304/19/23
Air TemperatureAir Temperature
Instrument used to Instrument used to measure:measure: ThermometerThermometer
Units:Units: °C, °F, °K°C, °F, °K
How it is shown on How it is shown on a weather map:a weather map: IsothermsIsotherms
Important Information:Important Information: Solar radiation is the Solar radiation is the
main source of heat main source of heat energy for the energy for the atmosphere.atmosphere.
The amount of solar The amount of solar radiation is affected radiation is affected by:by: Hours of sunlight/dayHours of sunlight/day Reflection, refraction, Reflection, refraction,
and absorbtionand absorbtion
Isotherms Isotherms
Air PressureAir Pressure Instrument used to Instrument used to
measure:measure: BarometerBarometer
UnitsUnits cm, inches, millibarscm, inches, millibars
How it is shown on a How it is shown on a weather map:weather map: Isobars, H and L Isobars, H and L
pressurepressure
Important Information:Important Information: Affected by altitude, Affected by altitude,
temperature, and temperature, and moisture content.moisture content.
Warm air = less dense = Warm air = less dense = low pressurelow pressure
Cold air = more dense = Cold air = more dense = high pressurehigh pressure
Dry air = high pressureDry air = high pressure Moist air = low pressureMoist air = low pressure High altitude = low High altitude = low
pressurepressure Pressure differences Pressure differences
affects wind speedaffects wind speed
Moisture in the AirMoisture in the Air Instrument used to Instrument used to
measure:measure: Hygrometer, Hygrometer,
psychrometerpsychrometer UnitsUnits
% relative humidity% relative humidity °C, °F Dew point °C, °F Dew point
temperaturetemperature How it is shown on a How it is shown on a
weather map:weather map: Dew point temperature Dew point temperature
is shown on a station is shown on a station modelmodel
Important Information:Important Information: Dew point temperature is Dew point temperature is
the temperature at which the temperature at which air is saturated. air is saturated.
Relative Humidity is the Relative Humidity is the ratio of the amount of ratio of the amount of water vapor in the air to water vapor in the air to the maximum amount that the maximum amount that it can hold at that it can hold at that temperature.temperature.
Absolute humidity is the Absolute humidity is the number of grams of water number of grams of water vapor in one cubic meter of vapor in one cubic meter of air. air.
Air MovementAir Movement Instrument used to Instrument used to
measure:measure: Anemometer (speed)Anemometer (speed) Wind Vane (direction)Wind Vane (direction)
UnitsUnits Km/h, mi/h, knotsKm/h, mi/h, knots N, E, S, WN, E, S, W
How it is shown on a How it is shown on a weather map:weather map: Isotachs or on a station Isotachs or on a station
modelmodel
Important Information:Important Information: Wind ALWAYS blows from Wind ALWAYS blows from
high pressure to low high pressure to low pressure and is influenced pressure and is influenced by the Coriolis Effect.by the Coriolis Effect.
In High pressure In High pressure (anticyclone) winds blow out (anticyclone) winds blow out from the center and from the center and clockwise.clockwise.
In Low pressure (cyclone) In Low pressure (cyclone) winds blow toward the winds blow toward the center and center and counterclockwise.counterclockwise.
Air TransparencyAir Transparency
How it is shown on How it is shown on a weather map:a weather map: a station modela station model
Visibility:Visibility: Horizontal distance Horizontal distance
the eye can see (mi)the eye can see (mi) Cloud Cover:Cloud Cover:
Fraction/percentage Fraction/percentage of the sky that is of the sky that is obscured (covered) obscured (covered) by cloudsby clouds
Cloud Ceiling:Cloud Ceiling: The base height The base height
(bottom) of the (bottom) of the cloud layers.cloud layers.
Measure with a Measure with a ceilometer which ceilometer which uses light pulses uses light pulses and photoelectric and photoelectric telescope.telescope.
Base height