Meteorology, Atmosphere, and Weather: Key Concepts and Timeline

Why is the atmosphere important

gases in air protect from sun rays and mix of gases in air allow life to flourish

weather

state of atmo in particular place and time

- air temp

- air pressure

- clouds

- wind

- precepitation

climate

average weather over specific time

- accumulation of weather events including extreme weather events

meteorology

study of atmo and phenomena

timeline of meteorology

- 340 BC Aristotle's Meteorologica

- 1400s-1600s weather instruments

- 1843 telegraph

- 1920 air masses / weather fronts

- 1940 upper ballon observations

-1950 num models/weather predictions

- 1960 satellites

geostationary satellite

orbits the same speed as earth's rotation and continuously observes what is happening

-22300 miles above earth

middle lat cyclonic storm system

- forms outside tropics and nh

- low pressure system

ex: hurricane, thunderstorms, tornadoes

What is wind?

Horizontal movement of air.

Fronts

boundaries that separate warm and cold air where there is a sharp change in temp, humidity, and wind direction

What does the direction of wind indicate?

Where it is blowing from.

What is wind speed?

Rate the air is moving past a stationary observer.

early atmo

- mostly comprised of hydrogen and helium

- outgassing of co2 and h2o escaping from the earths cooling core caused rain

- lake and oceans formed and absorbed co2 from atmo

- plants evolved producing oxygen

Composition of today's atmo

-99% of atmo within 20 miles of earth's surface

-78% N2 21% O2 and small amounts of gases

standard sea level pressure

1013.25 mb

Density

largest as move toward surface

Lapse Rate

The rate at which temperature decreases with an increase in altitude.

- decreases from surface to about 11 km

temperature inversion

rate that temperature increases with height

troposphere

where we live

What is the second layer of the atmosphere?

Stratosphere

How high does the stratosphere extend?

From 10 to 30 miles up

What layer is located in the stratosphere?

Ozone layer

What percentage of ultraviolet radiation is absorbed by the stratosphere?

95%

How does temperature change with altitude in the stratosphere?

Temperature increases with altitude increase

Mesosphere

3rd layer of the atmosphere

-temperature decreases with altitude

Thermosphere

The uppermost layer of the atmosphere, in which temperature increases as altitude increases

radiosonde

an instrument used for gathering upper-atmospheric data

- can be used on weather ballons twice a day measurements

temperature

how hot or cold something is based on standard reference point

-measure of average speed of the atoms and molecules

- measure of kinetic energy

Celsius

references waters freezing point

C= 5/9 (F-32)

Fahrenheit

scale of human experience

Kelvin

is an absolute scale

K= C+273.15

heat

The energy transferred between objects that are at different temperatures

Energy

capacity to do work

conduction

Heat transfer from molecule to molecule within a substance: touching a metal pan

-important near ground

Convection

heat transfer by a fluid (water or air) warm less dense air rises

vertical motion: convection advection: horizontal motion

-cloud formation as warm moist air rises

Radiation

Heat transfer that does not require the substances touching or a fluid between them: energy from the sun

- electromagnetic waves

- shorter the wavelength= more energy it carries

-energy from sun

Stefan Boltzmann Law

The relationship stating that an object emits energy at a rate proportional to the fourth power of its temperature, in Kelvins.

Solar Radiation

- shortwave

- visible part of the spectrum

- allows us to see other things

earth's radiation

- not visible

- less energy

- longwave

Kirchoff's Law

Objects that are good emitters of radiation at a given wavelength are also good absorbers of radiation at that wavelength

Blackbody Radiation

Objects that absorb all radiation hitting them and emit all possible radiation at their temperature

Radiative Equilibrium

radiation absorption = radiation emission

- on avg planet does not heat nor cool

What does ozone in the stratosphere absorb

UV radiation protecting us from sunburn

What does water vapor, carbon dioxide, and methane absorb

longwave radiation but not shortwave

incoming radiation from sun

- 19% absorbed by the atmosphere

- 26% reflected and scattered back to space by clouds, aerosols and atmo

- reflected 4% ice and snow

- absorbed by surface 51%

Albedo

solar radiation reflected by things in the atmo and surface

- 30%

outgoing radiation from earth

- longwave

- 94% absorbed by the atmo as it is opaque

- radiation is emitted back to surface causing the temperature we live in now

greenhouse effect

- surface of the earth is warmer than it would be without atmo because rad is from sun and atmo

Latent Heat

heat absorbed or radiated during a change of phase at a constant temperature and pressure

earths annual energy balance

- high lat lose more energy to space than received by the sun

- low lat retain more energy than lost

- energy transferred from tropics to poles

balance @= 38 degrees

At night clouds...

absorb longwave radiation and emit back to the surface

During the day clouds...

higher albedo and less shortwave radiation reaching the surface

Earth is tilted on its axis

23.5º

-reason for seasons

Equinox

day and night are the same length

- directly over equator

- March 20/September 22

Solstice

- longest day of year in nh: June 21

- shortest day of year in nh: December 21

vise versa

Meteorological

DJF (winter), MAM (spring), JJA (summer), SON (fall)

Sunspot

cooler dark regions

Corona

2 million Celsius

Photosphere

what we see 6000 C

Chromosphere

cooler region between the photosphere and corona

solar flares

- jets of gas that shoot into the corona

- disrupt earth's magnetic field

Aurora

- charged particles from solar wind that excites atoms in upper atmo

- diff elements give diff color lights oxy= red/green nitrogen= red/violet

- higher lats

nocturnal inversion

surface is colder than air above the surface

- strongest when calm, clear, dry night

How does humidity effect diurnal range?

-haze during the day prevent some of suns energy from hitting the surface

- at night humid air absorbs for outgoing infrared radiation

methods of protecting crops from cold night air

-cover

- orchard heaters

- wind machines

- irrigation

- ice it down

Mean Temperature

average of the high and low temperature for the day

Normal temperature

30 yr average of high or low temperature

What controls temperature?

- latitude

- land/water distribution

- ocean currents

- elevation

Isotherms

lines of constant temperature

Heating degree day

- people begin to use heating indoors when average daily temp below 65 degrees

65 degrees- mean temperature= heating degree day

cooling degree day

people begin to use cooling indoors when average daily temperature is above 65°F

- mean temperature- 65 degrees= cooling degree day

Growing Degree Day

mean daily temp 1 degree above the base temp for a crop

Sensible Temperature

body's perceived temp

Frostbite

skin freezes and discolors

Hypothermia

abnormally low body temperature

- mostly happens between freezing and 50 degrees as the wet maters

- water on exposed skin conducts heat away from body faster

standard cooperative station thermometer

- 2 m above ground in white shelter

- doors open to the north

- vented sides

- grassy area

Saturation

occurs when the amount of water vapor molecules escaping the liquid as entering are the same

- max amount of water vapor in the air

- hotter water molecules are moving faster= more in air

the hotter it is the greater

amount of moisture that can be in the air thus warmer you are the more the water vapor at saturation

absolute scale

tells you value of something in its entirety

ex: Kelvin, dewpoint temperature, specific humidity

relative scale

tells you the value of something compared to some reference point

ex: Fahrenheit and Celsius

Relative Humidity

compares the amount of moisture in air with the amount needed for saturation at a particular temp

RH: (actual wv/ saturation wv)* 100

Condensation

The change of state from a gas to a liquid

- occurs on condensation nuclei ex: dust, salt, etc

hygroscopic

water seeking wv condenses on them easily

Hydrophobic

condensation won't occur on them

Dewpoint

- temp needed to cool the air to get saturation

- forms on objects near the surface when they cool below this

Wet Bulb Temperature

measure of the heat stress in direct sunlight taking account of temp, humidity, wind speed, sun angle, and cloud cover

Psychrometer

used to obtain dew point and relative humidity

Hygrometer

instrument that measures humidity

ex: electrical hygrometer, dew point hygrometer

frost

cools to the dew point and dew point is below freezing

haze

- dry condensation nuclei reflect and scatter sunlight creates blue color

- wet condensation nuclei reflect and scatter sunlight grayish or white

fog

- saturation is reached and condensation creates cloud near ground

Radiation Fog

ground cools through conduction and radiation

- forms best with shallow moist layer @ ground

- calm winds

Advection Fog

warm moist air moves horizontally over cool surface

- summer fog on pacific coast

Upslope Fog

moist air flows up an orographic barrier

Luke Howard

- maintained a record of accurate thermometer and barometer readings

- father of cloud classification

Stratus

layer

- uniform gray

- resembles fog that does not reach the ground

- no precipitation

Cumulus

heap

- puffy cotton

- flat base round top

- more vert developments

Cirrus

to curl hair

nimbus

rain

High Clouds

- above 16,000 ft at mid lat

- white in day, red/orange/yellow at sunrise

- types: cirrus, cirrostratus, cirrocumulus

middle clouds

- 7,000-23,000 ft

- types: Altostratus, altocumulus