Meteorology Today Flashcards

Terms Definitions
Frozen dew
Hydrophobic Nuclei
Mammatus clouds
adds nitrogen
warm clouds
above freezing
add oxygen
photosythesis and decomposition
The instrument that measures temperature, pressure, and humidity at levels above the earth's surface is the_____.
The force per unit area.
What are geostrophic winds?
Winds aloft
change from ice to vapor
macro-scale motion
synoptic + planetary scales
In the Northern Hemisphere, surface winds tend to blow clockwise and outward around an area of high pressure.
Heat transfer process that depends upon the movement of air.
An utraviolet photon carries more energy than an infrared photon
Any gaseous, chemical, or organic matter that contaminates the atmosphere, soil, or water.
Tropical air masses
warm, indicated by "T"
_____________ stable air parcels cool off more slowly than the dry adiabatic laps rate but faster than the moist adiabatic lapse rate as they rise.
development or strengthening of a middle latitude cyclone
Bergeron Process - water evaporate from water droplets and migrates to ice crystals, so ice crystals grow at expense of water droplets
Typical size of a cloud droplet
1/1000 bar, common unity of measurement for pressure
The planet whose atmosphere is mainly nitrogen and oxygen.
The electrified region of the upper atmosphere.
A temperature scale where O degrees represents freezing and 100 boiling
A colorless and odorless gas that occupies about 21 percent of dry air in the lower atmosphere.
Acid Rain
Cloud droplets or raindrops combining with gaseous pollutants, such as oxides of sulfur and nitrogen, to make falling rain (or snow) acidic- ph less than 5.0. Acid fog forms with fog combines with such pollutants.
A hypothetical object that absorbs all of the radiation that strikes it. It also emits radiation at a maximum rate for its given temperature.
The process by which water vapor becomes a liquid.
The partial freezing of exposed parts of the body, causing injury to the skin and sometimes to deeper tissues.
Environmental lapse rate
rate at which environmental temperature changes (surrounding an air parcel)
What is an example of remote sensing?
What measures wind direction, arrow points into the wind?
Wind vane
Lee cyclogenesis
Westerly winds over N-S mountains cause lee-side lows so the wind curves cyclonically which strengthens cyclogenesis
Orographic clouds
clouds formed by lifting along topography
Condensation level
Altitude at which the relative humidity reaches 100%
greenhouse effect
gases in the troposphere trap radiation, making Earth's temps higher
Relative humidity can be high, with very little water vapor in the air, when the air is _______.
__________ cooling occurs at night as the earth's surface and the air above it give off infrared energy and lose more energy than they receive.
the condition of the atmosphere over many years
Dew Point
Temperature at which the relative humidity reaches 100%
In the upper atmosphere, the mean free path of atoms and molecules decreases with increasing altitude.
The highest level of the ionosphere is called the D region.
A perfect absorber and a perfect emitter of radiation is called_____ ______
black body
This is released as sensible heat during the formation of clouds
latent heat
An air temperature of 0 degrees K would be the same as an air temperature of 0 degrees C.
The condition of the atmosphere at any particular time and place.
Fahrenheit scale
A temperature scale where 32 is assigned to the temperature where water freezes and 212 to the temperature where water boils.
A faint glow of light emitted by excited gases in the upper atmosphere. Air glow is much fainter than the aurora.
A general term that refers to the air's water vapor content.
Radiation Inversion
An increase in temperature with height due to radiational cooling of the earth's surface.
Radiational cooling
The process by which the earth's surface and adjacent air cool by emitting infrared radiation.
A process that takes place without a transfer of heat between an air parcel and the surrounding air is called an __________ process.
How accurate is the 12-24 hours forecast?
Quite accurate
constant height chart
a chart that describes atmospheric pressure changes at a constant level (like sea-level)
rain gauge
any instrument that can collect and measure rainfall
What is an example of an in-situ?
A thermometer
Lens shaped clouds formed as air moves over a mountian
What humidity measuring device is a satellite instrument that measures humidity by measuring the amount of infrared energy absorbed by vapor?
Infrared hygrometer
_____ drops grow faster than ______ drops.
larger, smaller
Most of the ozone in the atmosphere is found in the atmospheric layer called the _____.
The ratio of the mass of a substance to the volume occupied by it. Air density is usually expressed as g/cm^3 or kg/m^3.
Wien's Law
A law of radiation which states that the wavelength of maximum emitted radiation by an object (ideally a blackbody) is inversely proportional to the object's absolute temperature.
Saturation Vapor Pressure
The maximum amount of water vapor necessary to keep moist air in equilibrium with a surface of pure water or ice. It represents the maximum amount of water vapor that the air can hold at any given temperature and pressure.
Triple point
the point where the cold, warm, and occluded fronts come together in an advanced occlusion front of the middle latitude cyclone. At this point, storm dissipates because the warm sector of the open wave is removed and there is cold air on both sides of the front
What is the typical rawinsonde output type?
Skew-T log-P diagram
What are keys to upper level development?
Postion of shortwaves
What are four devices to measure temperature?
Liquid-in-glass thermometer, electrical resistance thermometers, thermisters, and satellites.
The relationship between atmospheric pressure and density
atmospheric pressure and density decrease with altitude exponentially
Conditional instability occurs when....
the environmental lapse rate is between the dry and moist adiabatic rates.
trade winds
wind belt between 30 and 0 (equator) degrees
Occluded front
cold front catches up with warm front so they mix, with cold air behind and not-so-cold air ahead (purple line with symbols to indicate direction)
The so-called "ozone hole" is observed above:
the continent of Antarctica
The proper order of waves from longest to shortest is:
infrared, visible, ultraviolet
Sensible heat
The heat we can feel and measure with a thermometer.
Growing degree-day
A form of the degree-day used as a guide for crop planting and for estimating crop maturity dates.
What is the Trend Method?
Weather systems won't change movement or direction unless something impacts them to do so.
Neutral Stability occurs when...
the environmental lapse rate is the same as the adiabatic rate, so the air neither rises nor falls.
What can't the models do?
Represent the entire atmosphere, so there are approximations that retain the most important aspects of the atmosphere's behavior.
What type of air mass is continental tropical (cT)?
Hot and dry
Coriolis Function increases when...
wind speed, latitude, or the planet's speed of rotation increases
An air ______ is a small amount of air (a few meters wide) that is considered as a single unit in explaining the behavior of air.
What is the most basic way to measure humidity?
Sling psychrometer
What is a rawinsonde?
An instrument used to obtain the vertical distribution of temperature, pressure, humidity, and winds.
What is remote sensing?
The instrument is measuring the state of the variable at a location other than that of the instrument.
Dry adiabatic rate
10C for every 1000m or 5.5F for every 1000ft (Temp. change for unsaturated air parcels)
What type of air mass can keep adding moisture to the air without becoming saturated?
Warm air mass
When do we use the GFS model?
To start the NAM model.
What is velocity folding (aliasing)?
A radar has a 'maximum unambiguous velocity' as well. It is the maximum velocity the radar can measure with certainty. Lambda is the wavelength of the radar (expensive to change; it is fixed by type of radar). If an object is moving too rapidly away from the radar, the returning wave will be phase shifted by one whole wavelength. Velocity folding is shaded in purple. V_max=PRFλ/4
In Anticyclonic Flow, the inward ____ force is greater than the outward ____ force, causing centripetal acceleration.
Coriolis Force, Pressure Gradient Force
What is the Analogue Method?
Current situation may resemble one of the past, so what happened 2 or 3 days after that past situation? But no two situations are exactly the same.
Mechanical Equilibrium
The body (of air) is at rest and the sum of all forces acting on the body is zero.
What are the cons to automation?
There is no backup when equipment fails. Lack of detailed remarks on sky conditions and present weather. Expensive to have both observer and ASOS in same location (but good for employment of meteorologists.)
How do we get weather charts today?
Computers now produce weather charts, although the computer does not do it as well as a human would.
What is the main source of error in the models?
The inaccurate formulation (the assumptions) of the model.
What is the output from the computer know as?
Guidance because the forecaster must determine how good the computer forecast is and how it applies to his/her area.
When there are horizontal differences in pressure...
air moves from high to low pressure areas in order to balance the pressure.
What are the advantages of the network wind profilers over rawinsondes?
They provide hourly averaged wind profiles every hour. Measure winds almost directly above each site. Operate reliably and unattended in nearly all weather conditions. Provide temporal and spatial density of soundings needed to compute derived fields for the first time.
How did the radiosonde used to be tracked?
It was tracked using a radiotheodolite, which received a radio signal from the sounding. This signal was used to determine the changing location of the sounding with respect to the launch site, allowing for the wind speed and direction to be determined.
How can we analyze a system using water vapor imagery?
We can overlay hourly RUC analysis upper level fields (vertical motion, divergence, jet streaks) on top of satellite imagery to help us understand. This method can also help us determine when a model/ analysis is wrong-when it doesn't match what we see in the water vapor.
What other things can radiometers do?
It can measure the amount of rain that has fallen over an area, can also gather info about the land, and assessment of pollution and haze, cloud heights, ozone in the stratosphere, much more.
Why are the first drops of rain large and heavy?
Because the larger drops fall fastest and reach the ground first.
In ASOS, what do we use to detect cloud heights?
Senses and reports cloud heights (to nearest 100 ft), vertical visibility, and sky coverage. Even though it only looks straight up, over time it gives a reasonable picture of cloud cover because cloud systems drift across the sky. 30 minute sample is used, weighted to last 10 minutes. Sky coverage is based on the number of cloud base readings made- may be inaccurate under rapidly changing conditions. Only measures up to 12,000 ft, can report no more than 3 different cloud height levels at a time. Cloud coverage is inaccurate if a cloud parks itself over the instrument. Cannot detect cloud type. Reports cloud bases lower than reality if precipitation or obscurations (fog, haze) are present. For cloud bases less than 2,000 ft, vertical visibility (VV) reports are issued in 100 ft increments.
What happens to the range when the power return diminishes?
It gets bigger. Range is squared to account for the loss of the power return diminishing
In ASOS, what do we use to detect lighting?
A lightning sensor. This is how ASOS measures thunderstorm activity. Select sites have a Single Point Lightning Sensor. Many more sites use the Automatic Lightning Detection and Reporting System which transmits National Lightning Data Network information. The lightning sensor can detect cloud-to-ground and cloud-to-cloud lightning 30 miles away from the station. Two strikes of lightning within a 15 minute period are required for a thunderstorm to be reported by ASOS.
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