ATOC 1050: EXAM 1
97 Cards in this Set
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Temperature is the measure of the average speed that molecules move in a substance.
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How is temperature defined?
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Degrees Fahrenheit for the surface, and degrees Celsius for the upper air.
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What units for temperature are used in meteorology in the US?
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Air temperature decreases with height in the troposphere. Air temperature increases with height in the stratosphere.
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How does air temperature change with height in the troposphere and stratosphere?
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The boundary between the troposphere and the stratosphere.
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What is the tropopause?
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It prevents vertical motions from moving into the stratosphere so that clouds do not grow any taller.
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How does the altitude of the tropopause affect the height of clouds in the troposphere?
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The force applied by air on a unit area of surface.
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How is atmospheric pressure defined?
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Millibar (mb)
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What units of pressure do meteorologists use?
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The atmosphere cannot contain any more water vapor without condensing into cloud droplets.
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What does it mean when people say "air is saturated"
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The amount of water vapor in the atmosphere relative to the atmosphere's capacity for moisture at a given temperature.
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What is relative humidity?
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The lowest temperature to which air can be cooled at constant pressure before saturation occurs.
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What is the dewpoint temperature?
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100%
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What is the value of relative humidity if the dewpoint temperature equals the air temperature?
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The "hidden heat" required for a phase change.
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What is latent heat?
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The movement of air.
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What is wind?
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The direction from which the wind is blowing
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What is the convention for reporting wind direction?
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Knots
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What units are wind speed reported in?
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Wind Speed
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What do wind barbs represents on a weather map?
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In the troposphere, the layer of the atmosphere between the ground and 12km (7.5 miles)
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Over what altitude range does most of Earth's weather occur?
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Temperature, pressure, density, moisture content, wind speed and direction, visibility, cloud cover and precipitation rate.
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What are the basic properties of the atmosphere used in describing weather?
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Ozone found in the stratosphere absorbs ultraviolet radiation increasing the temperature in this layer.
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Why does temperature typically increase with height in the stratosphere?
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Sea level is the altitude to which all station pressure measurements are corrected. The value is the pressure that a particular station would record if it were located at sea level.
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What is meant by "sea level pressure"
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Force per unit area applied by the water vapor molecules. The measure of the absolute amount of moisture in the air.
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What is vapor pressure?
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The vapor pressure at which air is saturated at a given temperature.
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What is saturation vapor pressure?
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the condition where air contains the maximum amount of water vapor for a given temperature and pressure.
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What is saturation?
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Vapor pressure and dewpoint temperature.
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What two variables describe the amount of moisture in the air?
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Measurements that are made simultaneously
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What are synoptic measurements?
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ASOS reports cloud height and amount, visibility, precipitation type, intensity and accumulations, obstructions to vision (fog, haze), wind direction and speed as well as character (gusts, squalls), pressure, altimeter setting, temperature, and dewpoint temperature.
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What does ASOS report? (Automated surface observing systems)
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A balloon-borne instrument package used to make measurements of atmospheric conditions above he surface.
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What is a rawinsonde?
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They are launched twice per day.
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How frequently does rawinsondes provide information?
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Pressure, temperature, dewpoint temp, wind direction and wind speed.
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What atmospheric variables do rawinsondes measure?
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Monitors precipitation and wing along the radar beam.
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What atmospheric variable does a radar monitor?
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The intensity of the returned microwave signal to the radar receiver is proportional to the rate rain is falling.
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How does radar determine rainfall rates?
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Type of doppler radar that operates in very high frequency and ultra high frequency radio bands. Measures winds up to ten miles up.
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What is a wind profiler?
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They work best in clear sky conditions
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When do wind profilers work best?
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Visible, infrared and water vapor
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What are the three primary channels used to create weather satellite images from Geostationary satellites?
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UTC is Universal Coordinated Time, GMT is Greenwich Mean time and Z is Zulu time. All indicate standard time in Greenwich, England
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What do the abbreviations UTC, GMT and Z mean?
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Answers will vary. For Colorado, subtract 7 from UTC to get local military time during non-daylight savings. Subtract just 6 during daylight savings.
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ow do you convert from Universal Coordinated Time to your local time?
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A graphical display of surface weather data for a single location over a period of time, typically hourly data for several hours.
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What is a meteogram?
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The entire troposphere and into the lower stratosphere. Balloon eventually explodes.
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What layers of the atmosphere does a rawinsonde sample during its ascent?
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The measurement of a vertical profile of atmospheric properties (typically made with a rawinsonde).
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What is a sounding?
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estimates the rainfall rate; the image indicates where precipitation of different intensities is occurring.
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What information does a radar reflectivity image provide?
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is a type of Doppler radar that uses a phased array of cables as the antenna.
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What is a wind profiler?
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is a depiction of the wind speed and direction at various altitudes in the atmosphere over a single location.
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What is a vertical wind profile?
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is a circular orbit lying in Earth's equatorial plane in which a satellite has the same rotational velocity as Earth.
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What is a geostationary orbit?
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temperature is in upper left (°F), pressure is coded in upper right, dewpoint temperature is in lower left (°F), wind speed indicated by barbs on end of staff (wind direction).
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How do you read temperature, pressure, dewpoint temperature, wind speed and wind direction on a station model?
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is the act of drawing lines of constant value for a variable on a map
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What is contouring?
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Isobars
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What are lines of constant pressure called?
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Isotherms
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What are lines of constant temperature called?
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Isodrosotherms
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What are lines of constant dewpoint temperature called?
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Both depict a three-dimensional surface on a two-dimensional plane.
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How are topographic maps of the earth's surface similar to constant pressure maps of the upper atmosphere?
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300, 250, 200 mb
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What constant pressure maps might you examine to locate the jetstream?
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Because pressure decreases with an increase in altitude. (It can be substituted for altitude.)
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Why can pressure be used as a vertical coordinate in meteorology?
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Is the difference between the temperature and the dewpoint temperature
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What is the dewpoint depression?
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A diagram of the atmosphere oriented in a vertical plane. This allows us to view the interior structure in the vertical. Imagine taking a slice of cake
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What is a cross section?
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the science of predicting future weather using mathematical models based on physical principles and solved on a computer.
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What is numerical weather prediction?
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consists of an interconnected set of mathematical equations describing the atmosphere's behavior.
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What does a computer model consist of?
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Inexact equations, errors in the initial weather conditions and inadequate resolution
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What are the three main factors that cause NWP model forecasts to degrade as the forecast range lengthens?
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refers to the approximation of particular physical processes rather than explicitly solving for every motion and phase change that occurs in the atmosphere.
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What is meant by "parameterization" in numerical models?
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Air pressure is the weight of the atmosphere above you
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What is air pressure?
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1013.25mb (hPS)
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What is standard sea level pressure?
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1mb=1hPa=100 Pa
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What is the conversions for mb to hPa to Pa?
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the atmosphere the pressure always decreases since there is now less atmosphere
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What happens to pressure when you go higher in the atmosphere?
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Warm air "holds" more moisture than cooler air.
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Warm air "holds" more moisture than cooler air.
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Saturation vapor pressure increases exponentially with increases in temperature.
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What is the relationship between saturation vapor pressure and temperature?
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The measured radial velocity adjusted so that the general storm movement is removed
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What is the storm relative radial velocity?
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Measures solar radiation reflected from Earth. Not useful if it is dark. Good for clouds, snow and land contrast
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What do visible channels measure?
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Measures IR wavelengths. The warmer the object the more IR radiation is emits. Good for cloud heights, works well in the dark
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What do infrared channels measure?
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Measures IR radiation with a frequency specific to water vapor.
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What does the water vapor channel measure?
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Visible, infrared, water vapor
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What are the three different types of satellite imagery?
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To simplify interpretation of the station data
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Why do we contour?
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Elongated region where the height of a pressure surface reaches minimum value
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What is a trough?
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elongated region where the height of a pressure surface reached maximum values
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What is a ridge?
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Boundaries between large air masses appear as strong temperature gradients
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What is a front?
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Strong bands of winds that flow parallel to a front on its warm side. Tend to move heart and moisture northward
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What are low level jets?
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bands of exceptionally strong winds that encircle the earth in the middle latitudes
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What is a jetstream?
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Exceptionally strong winds embedded in a jetstream
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What are jetstreaks?
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Fronts, low level jets and winds
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What do 825mb pressure maps measure?
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Moisture and clouds
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What does 700mb pressure maps measure?
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Steering winds for large storms
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What do 500mb pressure maps measure?
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Jet streams and jet streaks
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What do 300, 250 and 200 mb pressure maps measure?
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Observations of the atmosphere, use computer model forecasts, knowledge of local weather and experience
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How do weather forecasters make forecasts?
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Refers to the method of replacing processes that are too small-scale or complex to be physically represented in the model by a simplified process
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What are parameterizations?
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No wind chill is not a basic property
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Is wind chill a basic property of the atmosphere?
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It determines the air temperature
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How does the average speed of air molecules influence the atmosphere?
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at the tropopause
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Where in the troposphere is the temperature the coldest?
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troposphere, stratosphere, mesosphere, thermosphere
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Which of the following lists the layers of the atmosphere from lowest altitude to the highest level?
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the air is saturated and the relative humidity is 100%
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If the saturation vapor pressure is equal to the vapor pressure..
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increase, increase
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If the air temperature remains constant, adding water vapor into the air will _______ the dewpoint temperature and ______ the relative humidity
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7:00 AM on December 4
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If a map is created using data collected at 1400 UTC, December 4, what is the local date and time in Colorado?
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ASOS
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The weather data used to compile surface maps are obtained primarily from what instruments?
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Sounding
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What is the name given to the final weather product created with data gathered from a rawinsonde?
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Radar reflectivity image
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If you wanted to estimate the intensity of precipitation, what weather product would you exam?
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Cloud top temperature
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Which of the following is most representative of what is displayed on an infrared GOES satellite image?
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isodrosotherms
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Which is used to describe the dew point of temperature?
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isotherms
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On a surface map, a strong temperature gradient exists in a location where _____ are packed closely together
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height
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Isobars on constant height surfaces have their highest values in the same location where _______ contours have their highest values on a constant pressure surface
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A contour map showing the altitude (height) of the 500mb surface
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The approximate direction and speed of the wind at the 500mb level can be determined from what type of map?
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300mb
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What map would you examine to locate the polar jet stream?
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ATOC 1050: EXAM 1