Midterm Exam Flashcards
Weather
condition of the atmosphere at a certain time and place
Climate
- weather that is observed and measured over longer periods of time
- “average weather” of a region
Composition of the atmosphere
N2 - 78% of total volume of dry air
O2 - 21% of total volume of dry air
O3 - surface ozone (not good), smog, subways
Atmospheric Ozone (good)- upper atmosphere, natural, shields plants and animals from uv rays
H20 Vapor - variable 0-4%
Co2 - 0.038% of the air, GHG traps a portion of outgoing energy, as carbon dioxide increases so does average global surface temperature
Vertical structure of the atmosphere
density greater at surface, more molecule
- more dense at surface, weighs more, therefore pressure higher
- atmospheric/air pressure always decreases with heigh
Air temperature (vertical structure)
- more complicated
- Lapse rate = rate at which temperature increases or decreases with height
- temperature inversion - increases with height
Temperature
- average kinetic energy
- a measure of average speeds of atoms/molecules
- higher temperatures mean faster average speeds
Heat
- energy transferred from one object to another because of the temperature difference between them
Specific Heat
- capacity per unit of mass
- amount of heat needed to raise the temperature of one gram, one degree
water 1 cal/degree - water heats slowly, cools slowly, higher capacity for storing energy than soil/air
Latent heat
- heat energy required to change a substance from one state (phase) to another
- important for formation of weather
Conduction
- transfer of heat from molecule to molecule within a substance
- faster vibrating molecules
- flow from warmer to colder
Convection
- the transfer of heat by the mass movement of a fluid (liquids and gases)
- vertical exchange of heat
- thermals
- rising air- expands and cools, sinking air, compresses and warms
Why does earth have seasons?
- earth rotates around the sun
- elliptical path
- one spin = 24 hrs
- seasons regulated by the amount of solar energy recieved at the surface
- determined by the angle sunlight hits and for how long
- titl of the earth is 23.5 degree
- tilt always points in the same direction
- in NH, titled toward the sun in the summer, away in the winter
Radiant energy
- transfer of energy from the sun to an object
- travels in waves, electromagnetic waves
- shorter wavelengths, higher amount of energy carried
- streams of particles called photons
- all things, no matter how big or small, emit radiation
earth’s( terrestrial) radiation- longwave radiation
Sun’s radiation - shortwave radiation
Albedo
- percent of radiation returning from a given surface compared to the radiation initially striking the surface
- measure of reflectivity
Relative Humidity
- how close the air is to being saturated
- ratio of the amount of water vapor actually in the air to the max amount of water vapor required for saturation at a particular temperature
Dew point temperature
- the temp to which air would have to be cooled for saturation to occur
- higher dew points = higher water vapor content
Condensation Nuclei
particles in the air serve as a means for condensation to occur
Radiation Fog
- produced by earth’s radiational cooling (at night) MOST COMMON
Cirrus (high cloud)
thing, wispy clouds, blown by high winds into long streams, mare’s tails
Cirrocumulus (high cloud)
- small, rounded, white puffs, that may be singular or long rows
- mackerel sky, scales of a fish
Cirrostratus (high cloud)
- thin, sheetlike, usually covering whle sky, sun and moon can still be seen through them, Halo
Altocumulus (middle clouds)
gray and puffy, sometimes in waves or bands, one part of a cloud may be darker than another
Altostratus ( middle cloud)
- gray or blue gray, ice and water, cover entire sky, sun and moon dimly visible
Stratus (low clouds)
- uniform gray, covers entire sky, fog that doesn’t reach the ground, can’t see the sun
stratocumulus (low cloud)
- low, lumpy, clouds in rows or patches
Nimbostratus ( Low clouds)
dark, gray, rainy/snowy cloud
- scud (stratus/fractius) irregular clouds drifts
Vertical Development
cumulus - puffy, white, variety of shapes, top of cloud is the limit of rising air, thermals, “fair weather clouds”
Cumulonimbus - towering thunderstorm cloud with dark base extending up to the tropopause, a-lot of energy released through condensation can lead to violent updrafts and downdrafts
- stability and high level winds can create anvil shape
CB bulge - over shooting top into stratosphere
Weather satellites (2 types)
- Geostationary - orbit the equator at the same rate in the earth spins, remains at fixed spot, real time data
- Polar orbiting - closely parallel earth’s meridian lines, passing north and south
- lower altitude, more detailed images
Stable air
- air that is lifted or lowered will return to its original position
Unstable Air
- air that will move further away from original position - vertical air currents
Adiabatic process
- a rising parcel of air expands and cools, while sinking parcel is compressed and warms
- as long as air parcel is unsaturated the rate of adiabatic cooling or warming remains constant
Dry Adiabatic Rate
- 10 degrees celsius/ 1000 M
Moist Adiabatic Rate
- rate at which rising or sinking saturated air changes temperature, less than dry adiabatic rate - but not constant
6 degrees celsisu/ 1000 M is average
Absolutely stable
- when the environmental lapse rate is less than the moist adiabatic rate
Absolutely unstable
- when the environmental lapse rate is greater than the dry adiabatic rat e
Conditionally Unstable
- when environmental lapse rate is between dry and moist rates
Orographic Uplift
- forced lifting along a topographic barrier
Collision- Coalescence Process
- in clouds with tops warmer than -15
- liquid water
- collisions required different sized drops
- coalescence - merging of clouds droplets
The ice crystal (Bergeron) Process
- mid and high latitudes
- upper air below freezing (cold process)
- water droplets existing below freezing are supercooled
- difference in vapor pressure causes molecules to move from liquid drop to ice
- aggregation - ice crystals, colliding and sticking
Percip types
- Graupel - snow pellets
- most of our precipitation starts as snow
- Dry snow - snowflakes through colder, dry air tend to be small and powdery
- Wet Snow - snow falling through moist, slightly above freezing air melts some, attracts other snowflakes- makes bugger flakes
- MOST COMMON snowflake shape - Dendrite
Sleet
- if it falls through layer of below freezing air near the surface, it will freeze into an ice pellet
Freezing rain
- if that same cold layer is too shallow to freeze to a pellet, drops will be supercooled
Doppler Radar
- radar, radio detection and ranging
- brightness show intensity
- 1990s doppler replaced conventional, can detect speed, direction, distance, intensity
hail Formation
- form in highly convective clouds, cumulonimbus
- graupel, large raindrops or other particles act as embryo
- accretion - accumulation of supercooled droplets
- updrafts carry embryo to cold air
- as heavy ice falls, updraft kicks up again and again
Pressure
- horizontal difference in temperature creates differences in pressure
- this pressure creates - pressure gradient force
- air will move from high to low pressure
- the greater the difference, the stronger the force, the faster the winds
Winds
- warm air aloft - high pressure
- cold air aloft - low pressure
- horizontal difference in pressure
- the difference creates a force - pressure gradient force
- air will move from high pressure to low pressure
Low pressure System
- cyclonic - counterclockwise winds, inward
- centripetal accleration acts at right angles to the wind
- must be a net force, centripetal force keeps wind moving in circular direction
- imbalance between PGF, and CF
- light winds, weak, force
- strong winds, tight curve, tornadoes and hurricanes
Coriolis Force
- due to rotation of the earth
- deflection to the right in the NH, to the left in the SH
- zero deflection at equator, maximum at the poles
