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Definitions |
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Stratus
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...
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Upslope fog
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...
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Evaporation (mixing) fog
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...
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Electromagnetic waves whose wavelengths are shorter than those of visible light
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ultraviolet
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thermosphere filter
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some infrared rays
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ozone
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absorbs harmful UV rays
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Air that sinks, warms by_____
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compression
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Infrared Radiation
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Electromagnetic radiation with wavelengths between .7 and 1000 picometers. This radiation is longer than visible radiation but shorter than microwave radiation.
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nitrogen reservoirs
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air, soil, plants, animals
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high albedo
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light objects, rural areas
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Gas that strongly absorbs ultraviolet (UV) radiation in the stratosphere.
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ozone
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The wavelength range where neither water vapor nor carbon dioxide absorbs much of the earth's infrared radiation is known as the atmospheric_____.
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window
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The process of condensation, freezing, and deposition all release sensible heat in the environment.
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True
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Exosphere
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The outermost portion of the atmosphere.
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Thermograph
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An instrument that measures and records air temperature.
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Condensation _________ are solid (or liquid) particles in the air which serve as centers for water vapor to collect (condense) on during cloud formation.
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Nuclei
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thermosphere
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layer blends into space, temperature increases
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Cumulonimbus
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Thunderstorm cloud -> anvil shaped with extensive vertical development
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Frontolysis
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front weakens and dissipates because density drops, typical for slow fronts
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barometer
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an instrument that detects and measures pressure changes
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Do shortwaves move faster than longwaves?
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Yes
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The well-mixed region of the earth's atmosphere is known as the:
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homosphere
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The average decrease in air temperature with increasing height above the surface.
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lapse rate
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The earth's atmospheric green house effect is produced mainly by water vapor and carbon dioxide absorbing and emitting:
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infrared radiation
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Visible light given off by excited atoms and molecules in the upper atmosphere
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aurora
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Nitrogen
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A colorless and odorless gas that occupies about 78 percent of dry air in the lower atmosphere.
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Homosphere
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The region of the atmosphere below about 85 km where the composition of the air remains fairly constant.
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Heat
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A form of energy transferred between systems by virtue of their temperature differences.
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Deposition
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A process that occurs in the subfreezing air when water vapor changes directly to ice without becoming a liquid first.
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Isotherms
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A line connecting points of equal temperature.
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Does the smaller scale effect the larger scale and vice versa?
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Yes
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Where is the strongest lift located?
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500 mb
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ice embryo
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enough water molecules join together within the droplet in a rigid pattern to form a tiny ice pattern and it acts as an ice nucleus
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ground blizzard
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drifting and blowing snow after snowfall has ended creates poor visibility
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molecular viscosity
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friction flow because of random molecular motion
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What is TTAA format?
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Temperature, dewpoint depression, height of pressure level, wind speed and direction of mandatory levels.
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isobar
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a line connecting points of equal pressure on a pressure chart
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anticyclones
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at high pressure centers, air blows clockwise and outward
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Stationary front
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boundary between two contrasting air masses is not moving because winds are opposing, usually no precipitation (blue and red line with symbols to show direction of opposing air masses)
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westerlies
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wind belt between 30 and 60 degrees
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For the collision- coalescence process to occur, liquid water droplets of __________ __________ must be present.
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Varied sizes
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The thunderstorms that occur in our area during the summer form because of _____________.
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Convection
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A force exerted on a unit areas describes air
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pressure
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The two most abundant gases in the stratosphre are nitrogen and oxygen.
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True
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The combined albedo of the earth and its atmosphere average about_____ percent.
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30
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An increase in cloud cover around the earth would probably increase the albedo of the earth-atmosphere system.
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True
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Temperature Inversion
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An increase in air temperature with height, often simply called an inversion.
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Thermals
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A small, rising parcel of warm air produced when the earth's surface is heated unevenly.
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Absolute zero
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A temperature reading of -273C, -460F, or 0K. Theoretically, there is no molecular motion at this temperature.
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Evaporation
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The process by which a liquid changes into a gas.
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Cooling degree-day
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A form of degree-day used in estimating the amount of energy necessary to reduce the effective temperature of warm air. A cooling degree-day is a day on which the average temperature is one-degree above a desired base temperature.
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Water Upwelling
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wind along the coast forces warm surface water away from coast so deeper cold water rises to replace it
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cT air mass
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continental tropical air mass with warm, dry, unstable air
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synoptic-scale motion
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weather map scale, lasting days or weeks
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wind step 1
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warm near equator, cold near poles
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Shower
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raindrops are > 0.5 mu(m) caused by strong upward winds, or an updraft that suddenly weakens or changes direction- short and intensive precipitation
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When the winds converge, what possible signature is happening?
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A downburst
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How does a radiosonde measure wind speed and direction?
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A GPS
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Deposition nuclei
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ice nuclei on which vapor directly deposits as ice without becoming liquid first
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Sublimation
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The process by which a solid (ice) changes directly to a gas (water vapor)
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Ideal gas
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a simplified physical model for gas that neglects the volume of and the interaction between the individual molecules
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What is the average pressure for moisture?
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850 mb
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A measure of the average speed of air molecules
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temperature
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Latent heat
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The heat that is either released or absorbed by a unit mass of a substance when it undergoes a change of state, such as during evaporation, condensation, or sublimation.
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Heat capacity
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The ratio of the heat absorbed (or released) by a system to the corresponding temperature rise (or fall).
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Controls of temperature
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The main factors that cause variations in temperature from one place to another.
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What are rawinsonde drift characteristics?
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Maximum downstream displacement (to point of balloon burst): 200 miles. Burst level: 100 hPa to 2 hPa. Average ascent rate: 1000 feet/min (5 m/s). Typically reaches 200 hPa level (from near sea level launch) in 30 to 45 minutes. Ascent rate primarily affected by precipitation and icing. Balloon may be inflated with additional gas to compensate.
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What is parallel to earth's meridians (longitude lines), earth rotates underneath satellites, focuses on polar regions that are distorted by geostationary satellites, and orbits at 850 km- providing high detail?
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Polar orbiting satellites
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What is multispectral imaging capability?
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A 5-channel, high-resolution imager allows for the development of a number of advanced products.
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air density
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the mass of air in a given volume
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sea-level pressure chart
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a constant height chart using isobars to indicate changing pressure from place to place
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Moist adiabatic rate
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rate at which rising or sinking saturated air changes temperature; less than dry adiabatic rate and varies greatly; average change of 6C per 1000m or 3.3F per 1000ft
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Tropopause Jet Streams
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Subtropical; Polar- as a result of strong temperature gradients, there are strong westward winds and a meandering pattern that may merge or split, discontinuous
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At night objects on the ground cool by the process of emitting_____.
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infrared radiation
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Middle-Latitude Cyclonic Storm
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A cyclonic storm that most often forms along a front in middle and high latitudes.
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Mixing Ratio
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The ratio of the mass of water vapor in a given volume of air to the mass of dry air.
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What is ground data processing system?
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Provides efficient dissemination data and products to users.
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Absolutely Stable Atmosphere occurs when...
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occurs when the environmental lapse rate is less than the moist adiabatic rate(6C/km); small environmental lapse rate.
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Imperfect numerical weather predictions may result from what?
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Flaws in the computer models, errors that creep in along the model's boundaries, sparseness of data, inadequate representation of many pertinent processes and interactions due to inadequate model resolution, and inherently chaotic behavior that occurs within the atmosphere.
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Most precipitation starts as...
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snow and melts on the way down
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Conditional stability is dependent on whether or not...
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the rising air is saturated
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What are the wind profilers?
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They are specifically designed to measure vertical profiles of horizontal wind speed and direction from near the surface to above the tropopause.
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The Hadley Cell
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a cellular circulation of air in which warm air rises and cold air sinks, so that cold air from the poles moves to the equators at the surface, then rises as it warms and goes back to the poles aloft
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In a middle latitude cyclone, if surface convergence is aligned with divergence aloft...
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the storm will dissipate
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Two ways to grow raindrops besides condensation are____.
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Collision-Coalescence process and Bergeron process
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The two factors that regulate the relative humidity are the _________ and the amount of ________ _________.
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temperature and water vapor
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Daily (diurnal) range of temperature
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The difference between the maximum and minimum temperatures for any given day.
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In ASOS, how do we measure wind speed?
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Cup anemometer. Photointerrupter device (beam of light) on shaft counts the number of pulses in a given time.
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Absolutely Unstable air tends to...
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be warmer and lighter (less dense) than the environment, so it will continue to move vertically if 'pushed.'
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How does the radar work?
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The radar sends out an electromagnetic pulse. This pulse encounters objects and is scattered back to the radar. The larger and more plentiful the objects, the more energy will be scattered back. Measures reflectivity of snow and rain and a radar pulse volume at a range of 100 km is 1 km^3 (this is big).
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What is ACARS data?
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It represents a way of sending out data from in-flight aircraft- engine performance data, flight plan information, crew/dispatch messages, fuel loading, meteorological data. Available variables: latitude, longitude, altitude, time, temperature, wind direction and speed, measures of turbulence, dewpoint and icing info (a few aircraft). 140,000 wind and temperature observations per day, 100,000 of which are over continental US, coming from more than 4000 aircraft; more data during the day than night. Has been QC'd, very high quality, and no averaging is performed. Resolution: above 23,000 ft- every 5-6 minutes, below 18,000 ft- 1000-2000 ft in the vertical, and on ascent- could be up to 300 ft for first minute.
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Most snow occurs in ____ regions of US.
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Northwest, Northeast, and West
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Standard Atmospheric Pressure
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1 atmosphere = 1013.25 mb = 29.92 in. Hg = 76 cm Hg
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The saturation pressure above a water surface is ___ than an ice surface. Why?
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greater, because water molecules evaporate more easily.
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Is the Single Cell model accurate?
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No, because it is too simple.
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What type of air mass is continental artic (cA)?
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Extremely cold and dry
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What are the pros to automation?
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Many airports will have observations around the clock. Human observers freed for other tasks. Subjectivity eliminated- humans disagree on visibility observation 40% of the time, sky cover 15% of the time. High temporal resolution- for research and real-time needs and you can diagnose rapidly changing conditions.
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What do clouds at all levels have the same of?
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The same albedo
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A cyclonic flow the inward ____ force is greater than the outward _____ force, causing centripetal acceleration.
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Pressure Gradient Force, Coriolis Force
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What are the wavelengths for the different satellite images?
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Visible: 1km, Shortwave infrared: 4 km, Water Vapor: GOES west8 km and GOES east 4 km, Longwave infrared: 4 km, and Low level water vapor/ split window infrared (dirty window): 4km.
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What questions does forecasting ask?
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How and why will tomorrow be like today?
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A rising parcel of air...
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expands and cools due to lower air pressure surrounding the parcel, so it does work (causing cooling) to expand.
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What is ensemble forecasting and how does it hurt and help us?
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This approach runs several models, each with slightly different initial conditions. If the forecasts out to 24 hours agree, there is greater confidence in the forecasts- this particular weather situation is more predictable. The less agreement among the forecasts, the less predictable the weather.
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Convective formation of clouds
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warm air rises and condenses to form a cloud
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To maintain vertical air pressure in high centers,
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air converges at a higher altitude, sinks, and diverges at the surface.
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What is the first key to meteorology?
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The sun's heating varies over the earth and with the seasons.
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What was the old system replaced with and how will this change improve our data?
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The replacement radiosondes will use GPS (global positioning system) satellites to determine the location of the sonde, and thus the winds. According the NWS, the new system will: Improve data availability and accuracy, operate within a reduced frequency spectrum, be more efficient to operate and maintain, be more reliable, and distribute higher-resolution data that will provide better detail for input into numerical models.
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How often are rawinsonde observations taken?
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Twice daily at 0000 hours and 1200 hours in UTC time or at 7pm and 7am EST.
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Strong winds can't move fine particles on the ground because...
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there is a 0.1mm layer above the ground where the wind is practically zero.
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What time scale do we use in meteorology?
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Greenwich Mean Time (GMT) also called the Universal Coordinated Time (UTC) or Zulu time (Z).
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What is the difference between the NAM and the GFS models?
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The lines spread out farther in the GFS model (27 km) than they do in the NAM model (12 km).
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How do summer cP air masses form in North America?
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above northwest part of Canada and Alaska, the melting ice adds moisture to the cold air causing milder temps
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For ice crystals to grow large enough to produce precipitation, there must be a ratio of...
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1 ice crystal to 100,000 - 1,000,000 water droplets
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The albedo or the moon is 7 percent. This means that:
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7 percent of the sunlight that strikes the moon is reflected
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How do mP air masses form in North America?
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starts over Asia as cP, then moves over ocean and becomes mP because of moisture
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What is clear air mode and what do we use it for?
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The NWS FO's put the radar in this mode when there is no threat of precipitation (or sometimes when only light snow showers are present). This makes the radar extra sensitive-it can detect dust and insects in the air, allowing forecasters to pinpoint convergence lines where convection may soon fire.
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