Midterm Study Flashcards
Weather
State of the atmosphere at some place in time
What goes into weather?
Temperature, humidity, cloudiness
Meteorology
study of weather
NOAA Weather Radio
Continuous weather broadcasts
Climate
Weather conditions at some degree averaged over a specfied time period, typically 30 years
Time Zones
Measured east / west of the prime meridian
UTC or Z-Time
Based on Atomic clock, and expressed over 24 hrs.
No daylight savings time.
Pressure system
Features of atmospheric circulation, usually depicted as high or low.
High Pressure System
Anti-cyclones.
Always fair weathered, clockwise air rotation, outward (NH)
Low Pressure System
Cyclones
Wet weather, counterclockwise rotation, INWARD.
Air Mass
Huge volumes of air that cover hundreds of thousands of km2.
Gathers characteristics from the source region, such as temperature and humidity.
Cold Dry AirMass
Higher latitudes, continental
Cold Humid Air Mass
Higher latitudes, maritime surfaces
Warm Dry Air Masses
Over continents in subtropical regions
Warm Humid Air Masses
Near the equator or in the subtropics over maritime surfaces
Polar Air Masses
Colder in winter, milder in summer
Tropical Air Masses
Less seasonal variation due to uniform sunlight
How are air masses determined?
Take characteristics of the areas they pass over
Weather Front
Zone of transition between air masses of density, temperature, humidity, etc.
How do fronts work?
Three dimensional. Where the front intersects the Earth’s surface is shown with the symbols.
Warm Front
Clouds and precipitation occur over a wide band
may occur for 12-24 hrs with light precipitation
Cold Front
Narrow band
Heavy precipitation
Minutes to hours
How does wind affect weather fronts?
Wind directions are different on two different sides of a front.
How do weather systems affect coastal areas?
Lake / seas have lower summer temperatures
Maximum temperature
Happens early to mid afternoon.
Minimum temperature
Occurs around sunrise.
Dewpoint
Temperature when air is cooled at constant pressure so that it is saturated with water vapor and dew forms.
Relative Humidity
Compares the amount of water vapor in the air currently with the amount of water vapor in the SAME AIR if it were fully saturated.
How does RH change?
Through the day as temperature varies.
When is relative humidity the highest?
Around sunrise
When is relative humidity the lowest?
The warmest, so mid afternoon.
Air Pressure
Cumulative force exerted on any surface by the molecules composing the air. Expressed as the weight of a column of air per unit surface area.
Air Pressure Gradient
Change in air pressure over distance. Causes wind.
Wind direction
Direction the wind blows FROM.
West winds blow west TO east
Sky Cover
Fraction of sky covered with clouds
Weather watch
Issued by the National Weather Service when hazardous weather is possible.
Weather warning
Issued by NWS when hazardous weather is happening / imminent.
Geostationary imagery
High orbits, and orbits the planet at the same rate of Earth’s rotation.
Polar orbits
Low orbits, provides overlapping strips of images. Passes over the same point twice every 24 hrs.
Visible satellite image
BW, available during daylight. Reflective surfaces appear bright white.
Infrared satellite
Any time, provides temperature comparisons. Higher cloudtops appear whiter because they’re colder
Water vapor satellite image
Tracks down plumes of moisture, where whiter masses have increased moisture.
Cloud
Aggregates of tiny water droplets and ice crystals.
Atmosphere
Layer of gases and suspended particles enveloping the globe
Half of the mass is found within 5.5k of the Earth’s surface
Nebulae
Rotating interstellar clouds of dust, made of helium and hydrogen
Outgassing
Release of gas from molten rock / volcanic activity. Mainly CO2 , N2 and Water Vapor.
Carbonic Acid
Combination of rainwater in CO2.
Most abundant gas in the atmosphere
N2
then O2
Homosphere
Lower atmosphere
Circulates and maintains the ratios of gasses
Heterosphere
Upper atmosphere, results in layers of gas.
Oxygen and atmosphere stratification
O2 in Homosphere,
O in heterosphere
Split up by UV radiation
Aerosols
Liquid and solid particles
Can be from wind erosion, ocean spray, smoke, etc.
Water vapor
Occurs in the lowest 1km of the atmosphere. Necessary for clouds and precipitation
Carbon Dioxide
Required for life. Keeps the lower atmosphere warm, and can absorb IR radiation.
Air Pollution
Gas or aerosol that occurs at a concentration that can threaten the well being of organisms. Most are human made, but some are natural.
Primary Air Pollutant
Harmful immediately as emitted.
Secondary Air Pollutant
Harmful after combination with one or more substances
Photochemical smog
EPA’s standards for the 6 Air Pollutants
CO, Pb, O3, NO, Particulates, and SO2
Primary Air Quality
Maximum exposure levels humans can tolerate without effects
Secondary Air Quality
Maximum exposure levels able to minimize the impact on crops, visibility, etc.
Attainment areas
Geographic areas where standards are met, or below.
Non-attainment areas
Geographic areas where the primary standard is not met.
Conceptual model
Statement of a fundamental law.
Graphical model
Compiles and displays data in a format that conveys meaning, like a weather map.
Physical model
Miniaturized version of a system, such as a tornado vortex chamber
Numerical system
Mathematical equations help represent relationships among system variables.
Errors with models
Missing data
Accuract
ASOS
Automated Surface Observing System
Consists of sensors, computers, fully automated communication ports
Feeds data to NWS
Advection
Transferring one windmass to another place.
Mesoscale
More localized weather.
Synoptic scale
Wider in time and area.
Law of Energy Conservation
All solar radiation is connected 100%.
% Radiation Absorbed + % scattered + % transmitted = 100%.
Scattering
Small particles in the atmosphere are light or wavelength dependent. You cannot see air molecules, but these molecules scatter blue light.
Why are clouds white?
Clouds are large particles, and scatter all light.
Reflection
Special case of scattering.
Changes in direction of the wavelength as it hits the medium.
Albedo
Reflected sunlight off of a surface
How does albedo work?
The lighter the surface, the higher the albedo. Changes based on solar altitude.
When you have high albedo..
High reflection
Low Absorption
When you have low albedo..
Low reflection
High Absorption
How much does Earth scatter?
~30%
Greenhouse Effect
Heating of the earth’s surface and lower atmosphere by the strong absorption of IR from GH gases.
How does the Greenhouse effect work?
Allows shortwave radiation to pass through, emits IR radiation, being trapped and warms the greenhouse
Atmospheric Window
Radiation can pass into space with no absorption by the atmosphere
Absorption
Converts radiation to heat energy.
Ozone Shield
Steady decline in stratospheric ozone
Depletion happens over Antarctica every spring because of the increase in sunlight.
How does the ozone layer affect human health?
Less ozone, more UV, more cancer
Creation of ozone
UV radiation hits Oxygen
Creates two free oxygen atoms
Those collide with other molecules of O2 to create O3
Destruction of ozone
Ozone absorbs UV radiation
Splits into one free O atom and a molecule of Oxygen
Free atom collides with ozone to created two molecules of oxygen
CFC
Chlorofluorocarbons
Chemicals that deplete the ozone layer, banned in 1979 with the Montreal Protocol
Callendar Effect
Climate change can be brought by anthropocentric sources and increased CO2
Fossil Fuels
Approximately 75% of CO2 increases, 40% higher than pre-industrial era
Major causes of CO2 Increase
Rice farms, landfills, coal mining, etc
Pyranometer
Intensity of solar radiation that strikes a horizontal surface
Infrared radiometer
Instrument that measures the intensity of IR radiation emitted by the surface of some object such as land
Temperature
Average kinetic energy of atoms composing a substance
Internal Energy
Encompasses all energy in a substance (Kinetic + Potential)
Heat
Energy in transit. Energy moves from warmer to colder.
Absolute Zero
Theoretical temperature at which all molecular motion stops.
Calorie
Amount of heat required to raise temp 1g of water 1C degree.
Joule
Commonly used in meteorology
BTU
British Thermal Units
Amount of energy required to raise one pound of water one F degree.
Liquid in Glass thermometer
Mercury or Alcohol
Temperature gradient
Change in temperature over distance
2nd Law of Thermodynamics
Heat flows in response to a temperature gradient
Radiational heating
Absorption is greater than emission
Radiational cooling
Emission is greater than absorption
Conduction heating
Transfer of kinetic energy of atoms or molecules between neighboring atoms or molecules.
Material conductivity
Some materials are better at conducting heat than others.
Sensible heating
Conduction + Convection. Heating you can feel.
Convection
transport of heat within a fluid
Latent Heat
Heat given off from phase changes in water. Hidden and cant be tracked.
Melting
Solid to Liquid
Freezing
Liquid to solid
Sublimation
Solid to gas
Deposition
Gas to solid
Evaporation
Liquid to gas
Condensation
Gas to liquid
Thermal Inertia
Resistance to a change in temperature.
Maritime temperature change
Less contrast between winter and summer temperatures
Continental temperature change
Locations at the same latitude but well inland experience a greater contrast between winter and summer temperatures.
Earth’s Surface + Temp
Experiences radiational heating
Earth’s atmosphere + temp
Undergoes radiational cooling
Bowen ratio
Describes how heat energy is received at the Earth’s surface is partitioned between sensible and latent heating
Poleward heat
Heat transfer from the equator to the poles, done by air masses, storm systems, and ocean currents.
Storms and Poleward Heat
Tropical storms and hurricanes are greater contributors to poleward heat transport than cyclones
Heat Source
Surface is warmer than overlying air
Heat sink
Surface is cooler than overlying air
How is weather formed from heat transfer?
Imbalance of radiational heating / cooling
Heat distribution varies by season
Soil and heating
Bare soil warms more rapidly than moist soil.
Snow
High albedo, high reflection
Reduces sensible heating
Excellent IR emitter
Advection
movement of one air mass to another
Cold air advection
Horizontal movement of cold air to a warm area
Warm air advection
Horizontal movement of warm air to a cold area
Isotherm
Line of constant temperature
Heat Island
City of warmth surrounded by cooler air
Temperature difference greater at night with light winds
How do heat islands form?
Lack of moisture Concentration of heat sources Multiple reflections of sunlight Building materials conduct heat Low albedo
How to beat a heat island
Green roof
Increase albedo with white paint
Air pressure
Omnidirectional, exerts a force at all directions.
Force
Mass x Acceleration (-9.8g/s)
Dalton’s Law
All of the pressure exerted by an air mass is just a collection of the pressure from the COLLECTIVE gasses.
Barometer
Measures air pressure and monitors changes
Barograph
Barometer linked to a pen that records on a clock driven drum chart
Pascal
Unit of pressure
Worldwide standard, and sea level is 101,325Pa
Compression
Air is compressible.
Density and Altitude
Density and pressure drop with altitude
Horizontal vs Vertical variation
Horizontal variations are more important to meteorologists than vertical
Air pressure and influences
Temperature has more of an effect on air pressure than humidity
Hot Air Balloons
The air is heated, making it less dense, allowing the balloon to rise
Which is more dense? Hot or cold air masses?
Cold air. Cold air can hold more moisture due to Avogadro’s Law
Avogadro’s Law
At the same temperature and same pressure, air masses will have the same amount of molecules.
Warm and humid (Density)
Least dense.
Cold and dry (density)
Most dense.
Converging winds
Blow towards an air column
Diverging winds
Blow away from an air column
Anticyclones and pressure
Area where pressure is HIGHER than surrounding air
Surface winds blow Clockwise and Outward
Ideal gas law
Combination of Charles and Boyle’s Law
Pressure = Gas Constant x Density x Temperature
Expansional Cooling and Compressional Warming
(ADIABATIC) Law of Energy Conservation
Transfer of heat TO the parcel, temp increase
Transfer of heat from the parcel, Temp decrease
Adiabatic process
No heat is exchanged between an air mass and the environment.
Dry adiabatic lapse rate
Any parcel that is not saturated with water vapor
Atmospheric river
Band of concentrated water vapor transport. Responsible for the most horizontal flow of water.
Pineapple Express
Originates near Hawaii, flows toward the Northeast and makes landfall along the California coast
Water Vapor in the atmosphere
Most of it is in the troposphere
Conservation of water
Water changes phases, but never increases or decreases
Gravity and the water cycle
Gravity keeps the water from escaping to space
Transpiration
Water taken up by plant
Precipitation
Water that falls from the clouds to reach Earth
Mixing ratio
Mass of water vapor per mass of the remaining dry air expressed as so many grams of water vapor per kilogram of dry air.
Specific Humidity
Mass of water vapor per mass of air containing some vapor.
Absolute humidity
Mass of vapor PER unit of humid air
Saturation
Max amount of water an air parcel can hold
Pressure gradient
Different air pressure over water and over ice
Relative Humidity
Compares the amount of water vapor in the air with the amount of water vapor in the same air at saturation.
Atmospheric stability
Enhances or suppresses vertical motion of air
Stable air
Ascending parcel becomes cooler and more dense
Air stabilizes as it moves over cold surfaces
Absolute instability
Air temp is dropping more rapidly with altitude than dry adiabatic lapse
Conditional instability
Unstable for saturated, vice versa
What causes air to rise?
Ascending branch off current
Surface winds converging
Frontal Uplift
Contrasting air masses will meet
Warm front
Leading edge of advancing warm air
Goes above cold air.
Cold front
Leading edge of advancing cold air
Orographic lifting
Lifted by topography Expansional cooling (windward) and compressional warming (leeward)
LCL
Lifting Condesnation Level
Altitude at which the rising air becomes saturated and clouds from
Rain shadow
Dry conditions kilometers downward of prominent mountain ranges
Contrails
Stream of ice crystals formed in the exhaust of jetcraft
Cloud nucleus
Solid or liquid particles in the air
Essential for cloud formation
Hygroscopic nuclei
Nuclei that have a chemical reaction for water molecules
Cloud condensation nuclei
Promotes condensation at temperatures above and below freezing
Ice-forming nuclei
Promotes ice crystal formation
Deposition nuclei
Surfaces on which ice deposits directly from vapor
Supercooled water
Fresh water cooled below freezing point and still remains liquid.
Homogenous Nucleation
Ice embryos at a critical size
Cirriform
Wispy, stringy clouds
Stratiform
Layered clouds
Cumuliform
Puffy clouds
Altitude and cloud formation
Affects temperatures and composition
Temperature and cloud formation
Warm cloud ( >32f) Cold cloud (<32f)
High clouds
All have the prefix cirro
Composed of ice crystals
Middle clouds
Prefix of alto
Suprecooled water or ice
Flat and gray
Low clouds
Strato
Drizzle falls
Fog
Low cloud in contact with the ground
Restricts visibility
Dense fog
When visibility is 330 ft or less.
Radiation fog
Causes air near ground to saturate
Advection fog
PAsses over cool surfaces
Terminal velocity
Constant speed of a particle falling through a motionless fluid
Collision-coalescence
Occurs in warm clouds
Droplets have to be large enough so it overcomes the air
Virga
Streaks of water and ice falling from a cloud that vaporize beefore reaching earth’s surface
Rain
Flat spheres
unstable at diameters and break apart
Drizzle
Occurs in stratus clouds
Snow pellets
Conical particles of ice
Sleet
snowflakes partially melt below the cloud base
Hail
Forms in thunderclouds
Doppler effect
shift in frequency of sound or electromagnetic waves emanating from a moving source
Think of a train and how it moves differently and sounds differently based on its position
