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| where does most weather occur? |
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Definition
| the layer of the atmosphere 1.5 miles thick |
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Term
| basic properties of the atmosphere |
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Definition
| temperature, pressure, moisture content, wind speed and direction, significant weather (precipitation, visibility) |
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Definition
measure of the average speed that the molecules move in a substance
-faster the speed of molecules, higher the temperature |
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Definition
-Temp decreases with height up to about 7 miles (Troposphere)
-Above 7m temperature increases with height (Stratosphere) |
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Definition
-Boundary between Troposphere and Stratosphere
-Keeps air currents out of stratosphere
-Tropopause is higher up over equator and lower near the poles |
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| Subtropical and Polar Jetstreams |
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Definition
| circle the globe at 25 degrees and 50 degrees |
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Definition
-Above stratosphere
-Temp decreases with height |
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-Above Mesosphere
-Temp increases with height |
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Definition
| force applied by air on earth's surface |
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| -Weight of column of air above the surface area on earth at sea level |
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Definition
-Decreases with height
-Measured in millibars (mb) 1000dynes/centimeter^2
-measured with barometer |
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Definition
| invisible gas composed of individual water molecules |
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Definition
-force per unit area applied by only water vapor molecules
-measure of the absolute amount of moisture in the air |
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Definition
| -When the atmosphere cannot contain any more water vapor without condensing into cloud droplets |
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Term
| Saturation Vapor Pressure |
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Definition
the vapor pressure at which the atmosphere becomes saturated
-depends on temperature |
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Definition
-the amount of water vapor in the atmosphere relative to the atmosphere's capacity for moisture
-Determined by temp
Relative humidity = (vapor pressure/saturation vapor pressure) x 100 |
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Term
| Temp and Relative humidity |
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Definition
| As temp goes down, relative humidity goes up |
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Term
| Sat vapor pressure and temp |
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Definition
| Remember, the saturation vapor pressure always increases as the air temperature increases |
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Term
| relative humidity and temp |
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Definition
-The relative humidity is high when the difference between the temperature and dewpoint temperature is small.
-The relative humidity is low when the difference between the temperature and the dewpoint temperature is large |
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Term
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Definition
| The energy associated with the phase changes of water |
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Term
| Heat transfer (heating vs cooling) |
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Definition
-Latent heat is released from the water to the atmosphere as water goes from a gas to a solid (top to bottom of this figure).
-This causes the atmosphere to warm.
-Latent heat is absorbed by the water and removed from the atmosphere as water goes from a solid to a gas (bottom to top of this figure).
-This causes the atmosphere to cool |
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Term
| Universal Time Coordinate |
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Definition
-UTC is based on a 24 hour clock
-UTC never switches from standard time to daylight savings time |
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Term
| converting UTC to mountain time |
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Definition
| MST = UTC - 7 hours MDT = UTC - 6 hours |
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Definition
| Pressure Temperature Dewpoint Temperature Wind direction and speed Precipitation amount Precipitation type Present weather condition Visibility Cloud cover Cloud types Cloud ceiling (height) |
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Definition
| a balloon-borne instrumentation system that measures pressure, temperature, dewpoint temperature, wind direction, and wind speed |
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| A depiction of the vertical structure of the atmosphere |
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Term
| what determines how much microwave energy is returned to the radar? |
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Definition
| Size of precipitation particles Number of precipitation particles Type of precipitation particles (rain, snow, hail, etc.) |
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Term
| Decibel Radar Reflectivity dBZ |
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Definition
| logarithmic scale used when plotting radar reflectivity data to indicate the intensity of the microwave energy returned to the radar from targets (raindrops, hail, snow, etc) |
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Definition
| Position of precipitation Intensity of precipitation |
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Definition
| indicates the position and intensity of precipitation (like a regular radar) but can also estimate the radial wind speed from the Doppler shift of the transmitted and received signal. |
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Definition
•Temperature (deg F)
•Dewpoint Temperature(deg F)
•Coded SLP
•Wind speed and direction
•Cloud cover
•Significant Weather |
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Term
| Decoding sea level pressure |
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Definition
-If coded SLP is greater than 500: Put a 9 in front of the 3 digit coded SLP
-If coded SLP is less than 500: Put a 10 in front of the 3 digit coded SLP |
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Definition
| change in pressure over a given distance |
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| change in temperature over a given distance |
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| contour lines of constant dewpoint temperature |
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Definition
| an imaginary surface above the ground where the pressure has a constant value |
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| area of low heights on a constant pressure map |
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| area of high heights on a constant pressure map |
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Definition
-a measure of the local rotation (spin) in a flow
-Positive vorticity indicates counterclockwise spin. Negative vorticity indicates clockwise spin. |
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Definition
| contour line of constant wind speed |
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| band of strong winds that circle the earth at mid-latitudes |
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Definition
| region of exceptionally strong winds embedded in the jetstream |
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Term
| How do weather forecasters make forecasts? |
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Definition
-Observations of the atmosphere
-Use computer model forecasts
-Knowledge of local weather and experience |
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Term
| Numerical Weather Prediction NWP |
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Definition
| the science of predicting the future weather with computer models |
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Term
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Definition
a set of mathematical equations, coded into a computer
program, that describe the behavior of the atmosphere |
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Definition
Regional models - cover a limited portion of the atmosphere
Global models - cover the entire atmosphere |
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Term
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Definition
| an NWP model is run repeatedly with slight changes to the initial conditions or model formulation |
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Definition
| the average forecast of all the ensemble members |
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Definition
| the lowest temperature to which air can be cooled at constant pressure before saturation occurs |
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Term
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Definition
| lines of constant pressure on a map |
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Definition
-exists where the pressure changes over distance.
-Strong pressure gradient = fast winds |
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Term
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Definition
| lines of constant temperature |
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Term
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Definition
| Lines of constant dew point temperature |
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Term
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Definition
| a surface above the ground where the pressure has a specific value |
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Term
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Definition
difference between the temperature and the dewpoint temperature
-smaller value = more saturated |
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Definition
-useful for identifying fronts (boundaries between large airmasses)
-Winds flow parallel to height contours |
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Definition
| moisture distribution is prevalent on this map |
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Definition
| -used to determine the location of short waves and long waves associated with the ridges and troughs in the air-flow pattern |
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-located near top of troposphere
-jetstreams are prevalent |
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