Meteorology Unit 1

Meteorology

the study of weather variables, the processes that cause weather, and the interaction of the atmosphere with the Earth’s surface, ocean, and life

Climatology

the study of climate, including past climate conditions and possible climate changes in the future

Weather

the condition of the atmosphere at any time or place

weather variables

temperature, humidity, pressure, wind speed/direction, cloud cover, precipitation, visibility

climate

the condition of the atmosphere over many years

average high

30 year average high temperature for a given date and location

record high

the highest temperature ever recorded for a given date

atmospheric makeup

78% nitrogen, 21% oxygen, 1% argon plus carbon dioxide, ozone, and water vapor that vary in time and space

water vapor

0-4% of the atmosphere by volume, important for generation of day to day events (rain, clouds, snow, fog, etc)

condensation

the process of changing water vapor into liquid water

evaporation

the process of liquid water becoming water vapor

latent heat

heat released during phase change

carbon dioxide

0\.038% of the atmosphere; enters the atmosphere by decay of vegetation, volcanic eruption, exhalation of animal life, burning of fossil fuels; removed from atmosphere by photosynthesis, vegetation, oceans

ozone

0\.01% of the atmosphere; absorbed incoming radiation from the sun, natural shield for plants and animals; eye irradiation, throat irritation, vegetation damage

methane

0\.0001% of the atmosphere; effective absorber of thermal radiation emitted by Earth’s surface; sources of methane include coal mines, livestock, rice fields, gas pipelines

aerosols

suspended solid and liquid particles in the air, man made or dust/salt particles/ash from forest fires/volcanoes

pollutants

gasses and aerosols in concentration great enough to cause a nuisance or health hazard; includes auto emission (nitrogen dioxide and carbon monoxide) and fuel emission (sulfur dioxide)

how much of the atmosphere resides near the surface?

99\.9% due to gravity and compressibility

factors of atmospheric pressure

weight, mass, density, pressure, force

weight

the force acting on an object due to gravity (mass x gravity)

density

the amount of mass in a given space (mass/volume)

pressure

the force of the atmosphere acting on an area (force/area- air molecules are in constant motion, colliding 10 billion times each second. each time a air molecule bounces against a person, it gives a tiny push. this tiny force divided by the area is pressure)

force

the force of the atmosphere is the weight of the air (mass x acceleration)

pressure is:

isotropic (force exerted equally in all directions, more molecules in a column = greater pressure and less = lower pressure)

atmospheric pressure always ____ with ____ altitude

decreases, increasing

why does atmospheric pressure decrease with altitude?

atmospheric density decreases (fewer molecules banging into objects)

lapse rate

the rate at which temperature decreases (changes) with height

inversion

where the temperature increases with height

atmosphere can be divided according to:

pressure, temperature

troposphere

temperature decreases with height; average lapse rate 6.5 degrees celsius per 1000m; surface up to 6-10 miles (varies with latitude and season, higher in summer/tropics); temperature decreases with height because it is heated by the surface and not the sun; most weather happens here; 80% of atmosphere’s mass

stratosphere

temperature increases with height; up to 31 miles; temperature increases with height because the ozone layer absorbs ultraviolet light and warms up as a result; lack of mixing (wind) and turbulence; layered portion of atmosphere (“strata”); very little mixing occurs between the stratosphere and troposphere (except with thunderstorms and other strong storms), 99.9% of atmospheric mass resides below the stratosphere

mesosphere

temperature decreases with height; goes up to about 53 miles

thermosphere

temperature increases with height; goes up to about 75 miles, but there is no clear separation between the thermosphere and interplanetary space; the highest temperatures in the atmosphere are found in the thermosphere due to high energy radiation being absorbed by gases

ionosphere (upper level)

charged gas atoms that can reflect radio waves and aurora are found here

exosphere (upper level)

upper limit of our atmosphere; space begins here at about 350 miles

energy

the ability to do work on some form of matter

first law of thermodynamics

energy can neither be created or destroyed, energy lost during one process is gained in another

work

when matter is pushed, pulled, or lifted over some distance

potential energy

total amount of energy stored in any object (internal energy) determines how much work the object is capable of doing; a substance also possesses potential energy if it can do work when a chemical change takes place; PE = mass x gravity x height

kinetic energy

energy of motion; the faster something moves, the greater kinetic energy; KE = 1/2mv^2; if 2 substances have equal volume but different mass, the higher mass will have higher KE

internal energy

the total energy (potential + kinetic) stored in an object; temperature only indicates how hot of cold an air or water parcel is, but not about how much internal energy it possesses

temperature

a measure of the average speed of the atoms and molecules; measure of kinetic energy; average KE

the ____ average speed of the molecules the ____ the temperature

higher, higher

radiant energy

energy we receive from the sun

fahrenheit

only used in US and a few other countries; freezing point 32; boiling point 212

celsius

used in the majority of countries; freezing point 0; boiling point 100

Kelvin

used in mathematical and scientific operations; freezing point 273; boiling point 373

absolute zero

\-459 degrees fahrenheit, the slowest molecules can move

heat

energy in the process of being transferred from one object to another because of the temperature difference between them; total KE

zeroth law of thermodynamics

heat always flows from hot to cold

heat capacity

the ability of an object to store heat as it changes its temperature (ration the amount of heat energy absorbed by a substance to its corresponding temperature rise

specific heat

the amount of heat required to raise the temperature of 1g of that substance 1 degree celsius

water specific heat

4186

air specific heat

1005

sand specific heat

795

latent heat

the heat energy required to change a substance from one state to another; important source of atmospheric energy

evaporation

takes up heat from the environment; a cooling process

condensation

gives off heat from the environment; a warming process

energy always travels from regions of ____ energy to regions of ____ energy

high, low

conduction

molecule to molecule transfer; requires 2 objects to be in contact; depends on temperature between 2 objects and the thermal conductivity of those objects; air is heated not by the sun but by conduction with Earth’s surface

convection

vertical transfer of heat by movement of a fluid (hot air rises and is replaced by cool air)

radiation

transfer by electromagnetic waves; do not require a medium to travel through like conduction; in a vacuum travels at the speed of light, classified according to wavelength

advection

horizontal transfer of heat via mass movement of a fluid (heating by motion/wind)

wavelength

the distance between 2 wave crests

amplitude

half the height from the peak of the wave crest to the lowest point of the wave trough

waves are categorized based on

wavelength

the ____ the wavelength, the ____ energy the wave will have

shorter, more

electromagnetic spectrum

amount of radiation given off by the sun

longwave radiation

emitted by the earth (mostly IR), also called terrestrial radiation

shortwave radiation

emitted by the sun (UV, visible, Near-IR)

visible light

our eyes are sensitive to radiation between 0.4 and 0.7 micrometers

peak sun energy output corresponds with ____, wavelengths shorter than ____ are UV, wavelengths longer than ____ are IR

blue/green, violet, red

blackbody

a body which perfectly absorbs all incident radiant energy and perfectly emits the maximum radiation possible at a given temperature (the sun and earth can be treated as blackbodies, but not the atmosphere)

radiation can be:

absorbed, reflected, transmitted (ART)

scattering

the deflection of light by very small particles

reflection

when a surface redirects all or a portion of the incident solar radiation

why does the sky turn green during storms?

hail scatters light

colors of the sky

blue light is favored by our eyes; at noon sky/sun is white because all wavelengths of visible light strike our eyes; at sunrise/sunset molecules are scattered when they pass through thicker portions of the atmosphere

albedo

percentage of light that is reflected off of an object (the higher the albedo, the whiter the object)

average earth albedo

30% (energy not reflected is absorbed or transmitted)

factors that create seasons

angle of the sun (higher the sun angle = more direct radiation over a small area and less atmosphere to pass through); length of daylight (longer daylight hours = more energy available from the sun)

summer solstice

astronomical summer begins June 21; sun’s rays most direct in northern hemisphere

autumnal equinox

astronomical fall begins September 22; the sun’s direct rays across the equator

winter solstice

astronomical winter begins on December 21; sun’s rays are most direct in the southern hemisphere

Vernal Equinox

astronomical spring begins on March 20; the sun’s direct rays cross the equator

daytime warming

insolation strikes the ground and heats the surface; conduction in the lowest layers heats air molecules in contact with the ground

daytime heating

sun is highest at noon but max temp isn’t reached until afternoon; morning lows around sunrise daytime highs around late evening/afternoon; on a calm day air temp is warmer near surface but on a windy day mixing distributes heat upwards

night cooling

ground radiates energy out to space (radiational cooling); conduction of heat from lowest few inches of air into ground then out to space; nocturnal radiation inversion

nocturnal radiation inversion

air closest to ground loses heat rapidly

to get strong nocturnal inversion:

calm wind, no cloud cover, low moisture content, long nighttime hours

cloudy skies at night:

keeps outgoing radiation at the surface

latitude temperature

on average, temperatures decrease over land masses as we move from the equator to the poles

water’s impact on temperature

water is slow to heat/cool (high heat capacity), and so large bodies of water moderate local climate

ocean currents

transport warmer water near the equator towards the poles

elevation

air density decreases with elevation; fewer air molecules to warm by conduction

4 controls of temperature

latitude, land/water distribution, ocean currents, elevation

diurnal temperature range

the difference between the maximum and minimum daily temperatures in one day

mean daily temperature

average of highest and lowest day’s temperature

average annual temperature

average of 12 monthly temperatures

Heating Degree Day (HDD)

Assumes people use their furnace when the average daily temperature drops below 65 degrees fahrenheit; subtract the mean daily temperature from 65 degrees fahrenheit