METEOROLOGY

AtmosphereStudy of atmosphere is called METEOROLOGY. WEATHER – general condition of atmosphere at a particular time & place CLIMATE – general weather conditions over many years

Our atmosphere is a mixture of chemical elements and compounds. The most abundant element is NITROGEN and the most abundant compounds are CARBON DIOXIDE and WATER. O3 (OZONE) is another important substance in our atmosphere. It is important in the upper atmosphere to protect us from ULTRAVIOLET RADIATON, which cause SUNBURN and can lead to SKIN CANCER.

Oxygen in the Atmosphere:

Maintained by NATURAL PROCESSES that BALANCE the atmosphere.

Nitrogen in the Atmosphere: Nitrogen moves from AIR to SOIL to PLANTS & ANIMALS and then back again to the AIR.

Atmospheric Pressure:Ratio of WEIGHT OF THE AIR to the area of the surface on which it presses.At higher altitudes, LESS air therefore LESS weight which means LOWER pressureAt lower altitudes, MORE air therefore MORE weight which means HIGHER pressureFor example: YOUR EARDRUM WORKS TO EQUALIZE THE PRESSURE WHEN YOU FLY IN A PLANE

BAROMETER– instrument used to measure atmospheric pressure

Two Types: 1. MERCURIAL Barometer – uses liquid mercury (Std. Pressure = 760 mm Hg = 1 atm)2. ANEROID Barometer – “without liquid”, no Hg used – it’s a sealed container without air

LAYERS OF THE ATMOSPHERE:No distinct changes in pressure BUT do see changes in TEMPERATURE with increasing ALTITUDE.

TROPOSPHERE:• layer closest to earth•Temp. decreases as you go higher•Layer where weather occurs

STRATOSPHERE:•contains almost all atmospheric ozone•temperature increases as you go higher

MESOSPHERE:•temperature decreases as you higher•coldest layer of atmosphere

THERMOSPHERE:• temperature increases as you go higher• difficult to measure temp. here because air is so thin•contains 2 regions:oIONOSPHERE – transmits radio wavesoEXOSPHERE – last part of our atmosphere, borders with space

AIR POLLUTIONAny substance in the atmosphere that is harmful (examples: SULFUR DIOXIDE, CARBON MONOXIDE, LEAD )

ACID PRECIPITATION – gases from burning fossil fuels combine with water in atmosphere and form acids which fall as rain or snow

SMOG – general term for air pollution, combined term for smoke and fog

Solar Energy & Atmosphere

RADIATION – all forms of energy that travel through space as waves

LIGHT is the form that we see, but most is INVISIBLE to human eyes.

All of these make up the ELECTROMAGNETIC SPECTRUM and are referred to as ELECTROMAGNETIC WAVES.

CLOUDS, DUST and GAS MOLECULES affect the path of radiation from the sun and cause them to SCATTER.

50 percent absorbed by Earth20 percent absorbed by clouds30 percent reflected by clouds

ALBEDO– part of solar radiation reflected by a surface

GREENHOUSE EFFECT – process in which atmosphere traps infrared rays over earth’s surface•NECESSARY for life on earth as we know it

Radiation strikes more DIRECTLY at the EQUATOR and is more SPREAD OUT at the poles. Same amount of SOLAR ENERGY spread out over a larger area, therefore the TEMPERATURES are lower.

CONDUCTION energy transfer by direct contactCONVECTION energy transfer due to unequal heating

PRESSURE DIFFERENCES in the atmosphere at the EQUATOR and at the POLES created a general movement of air worldwide.

Winds

Global WindsSpinning/rotation of earth causes winds to move CLOCKWISE in the N. hemisphere and COUNTER-CLOCKWISE in the S. hemisphere. This is known as the CORIOLIS EFFECT.

TRADE WINDS – flow toward equator between 30o and 0o latitude

Meet at the equator in a “no wind” zone called the DOLDRUMS.

At other edge of the Trade Winds is another low/no wind belt known as the HORSE LATITUDES. WHY?

HORSES were thrown overboard to save water when ships weren’t moving

WESTERLIES – located between 40o – 60o latitudeEASTERLIES – from about 60o latitude to the poles

JET STREAMS– bands of high speed winds that exist in upper troposphere (can affect air travel)

LAND Breeze – dry cool breeze FROM land to sea

SEA Breeze – dry cool breeze FROM sea to land

LOCAL WINDS: often referred to as breezes, Named for where the winds come FROM

VALLEY Breeze – during the day, warm air FROM the valley moves up the slope

MOUNTAIN Breeze – during the night, cool air FROM the mountain moves down into the valley

Water in the Atmosphere

Water in the atmosphere exists in two forms other than water vapor. It can be SOLID AS ICE or LIQUID AS WATER DROPLETS.

EVAPORATION – phase change from liquid to gasSUBLIMATION – solid directly to gas (ex. dry ice at Halloween)DEPOSITION – vapor directly to a solid (ex. frost)

HUMIDITY – measure of amount of water vapor in the atmosphere

• SATURATED – air holds all the water vapor it possibly can

 RELATIVE HUMIDITY– ratio used to express amount of water vapor in the atmosphere

• Amount of ACTUAL water in the atmosphere with the amount of water that COULD be in the atmosphere.

PSYCHROMETER – instrument used to measure relative humiditySPECIFIC HUMIDITY – actual amount of moisture in the airDEW POINT – temperature to which air must be cooled to reach saturation.

If the dew point is below freezing, then DEPOSITION occurs and FROST forms. (direct from GAS to SOLID)

Clouds & FogResult from condensation of WATER VAPOR throughout the large volume of AIR.Requires the presence of solid particles, called CONDENSATION NUCLEI.

Air temperature changes as the air expands and is compressed. These changes are known as ADIABATIC CHANGES.

STRATUS – sheetlike clouds•Low base (almost at the surface)•Warm air lies above cool air•Variations = NIMBOSTRATUS, which are dark clouds that do produce heavy rain

CUMULUS – puffy vertical clouds•Forms as warm moist air rises and cools

•CUMULONIMBUS = variation of high, dark storm clouds

CIRRUS – highest clouds

•Wispy and feathery•Halo can be seen around the sun or moon, if viewed thru a cirrostratus cloud (light rays bend as they hit ice crystals)

FOG – a cloud that formed at the surface

PRECIPITATION – any moisture that falls from the air to earth’s surface

Precipitation

FORMS:

LIQUID Rain Liquid precipitation

LIQUID Drizzle Raindrops smaller than 0.5mm

SOLID Snow Most common solid, freezing up high and all

the way to the ground

SOLID Sleet Rain falls thru freezing layer at the ground

SOLID Freezing

rain

Rain falls and only freezes upon contact with

a solid surface (glaze ice)

SOLID Hail Lumps of ice form as winds blow frozen

substance back up into clouds repeatedly

Causes of Precipitation:A cloud produces PRECIPITATION when its droplets or ice crystals become LARGE ENOUGH to fall as RAIN or SNOW.

COALESCENCE – combination of different size water droplets to form large droplets that fall as raindrops

SUPERCOOLING – process where water droplets remain liquid at temperatures below zero degrees Celsius

FREEZING NUCLEI – special condensation nuclei that have crystalline structure similar to ice (required for precipitation to fall)

CLOUD SEEDING – process when freezing nuclei are artificially added to clouds to force precipitation to occur

WHY WOULD THIS BE USEFUL???• DROUGHT RELIEF• REDUCE SEVERITY OF LARGE STORMS

RAIN GAUGE – instrument used to measure amount of rainfall

WEATHER

Air Masses 

Differences in air pressure worldwide create WIND PATTERNS. Air moves from areas of HIGH PRESSURE to areas of LOW PRESSURE.

AIR MASS – large body of air with uniform/same moisture and temperature

NAME ABBREV. DESCRIPTION

MARITIME

POLAR mP MOIST, COLD

MARITIME

TROPICALmT MOIST, WARM

CONTINENTAL

POLARcP DRY, COLD

CONTINENTAL

TROPICALcT DRY, WARM

Four Main Types of Air Masses:

North American Air Masses:

3 Polar Air Masses:•cP Canadian – from Canada into the US•mP Pacific – from the Pacific near Alaska into the northwestern US•mP Atlantic – from the N. Atlantic into the New England states 4 Tropical Air Masses:•cT – only in summer, from southwest US to the northeast US•mT Gulf – froms in the Gulf of Mexico and moves to the eastern US•mT Atlantic – forms in the tropical N. Atlantic and travels to the eastern US•mT Pacific – forms in the N. Pacific and rarely reach land

When two unlike air masses meet, DENSITY differences keep them SEPARATE. The boundary that is formed between the air masses is called a FRONT.

Fronts

COLD Front:•Cold air mass overtakes a warm air mass & lifts it in the air•Produces stormsoSquall line – long line of heavy thunderstorms

 WARM Front: •warm air mass overtakes a cold air mass & rises over it

Four Main Types of Fronts:

STATIONARY Front: •2 air masses meet, but neither is displaced OCCLUDED Front: •fast moving cold front lifts a warm front completely off the ground

POLAR FRONT refers to the region where the cold air at the POLES meets the warm air of the MIDDLE LATITUDES.

These areas help create the beginnings of the low pressure storms known as WAVE CYCLONES.

WAVE CYCLONE – large storms that start typically along cold or stationary fronts

• big influence of middle latitude weather in the US

ANTICYCLONE – large storms that center on areas of high pressure

HURRICANES:• Severe tropical storm where winds exceed 120 km/hr

• Develop over warm tropical oceans

• Most destructive storms

• Called TYPHOONS in the Pacific

HURRICANE KATRINA: 8-28-2005

HURRICANE FRAN: 9-4-1996

THUNDERSTORMS – storm accompanied by thunder, lightning and strong windsTHUNDER – loud noise produced by the rapid expansion and collapse of air (caused by electricity rapidly heating the air with lightning

TORNADOES• whirling, funnel-shaped cyclone• smallest, most violent, and shortest-lived severe storm

• forms when thunderstorm meets high altitude horizontal winds which causes air to rotate

WATERSPOUTS – tornadoes over the ocean (or a very large body of water)

Weather InstrumentsTHERMOMETER – measures temperatureANEMOMETER – measures wind speedWIND VANE – determines the direction of the windRADAR – used to determine upper-atmospheric conditions

Forecasting the Weather

METEOROLOGISTS – (scientists that study the weather)

• They prepare weather maps that plot all the weather data gathered from many different sources.

ISOBARS – lines drawn to connect points of equal atmospheric pressure

• closely spaced = HIGH wind speeds• far apart = low change and LOW winds• circles = high (H) or low (L) pressure areas

CLIMATE

Factors that Affect ClimateAverage weather conditions of a region that occur over many years are referred to as CLIMATE.2 Major Components:

• TEMPERATURE RANGE – difference between high and low temp. of that assigned time period

• PRECIPITATION – any moisture that falls from the air to earth’s surface

Other factors such as LATITUDE, HEAT ABSORPTION & RELEASE, and TOPOGRAPHY influence climates as well.

LatitudeThe distance of a location from the equator determines SOLAR ENERGY and WIND PATTERNS.The amount of solar energy depends on: 1. ANGLE THE SUN’S RAYS STRIKE THE EARTH 2. NUMBER OF HOURS OF DAYLIGHT

Wind Patterns help determine: 1. HUMIDITY 2. PRECIPITATION 3. TEMPERATURE 4. CLOUD COVER EL NINO: periodic warming of the central Pacific Ocean that causes extreme weather on the western edge of North and South America.

Heat Absorption & ReleaseLand heats FASTER and to HIGHER TEMPERATURES than water because the WAVES and CURRENTS constantly move the water.

This can cause seasonal winds, called MONSOONS, which are common in Asia and bring heavy rainfall.

TopographyMountains influence TEMPERATURE and MOISTURE CONTENT of passing air masses.

• WARM air cools as it rises• COOL air warms as it descends

Climate Zones3 major climate zones: TROPICAL, POLAR, and the MIDDLE LATITUDES.

TROPICAL Climates:• Average monthly temp. of at least 18o

C• Influenced by cT and mT air masses• Examples: tropical rain forest, tropical desert, tropical savanna

POLAR Climates:• Temperature is never higher than 10o C

• Influenced by cP and mP air masses

• Examples: subarctic, tundra

MIDDLE LATITUDE Climates:• No warmer than 18o C in the coldest month• No colder than 10o C in the warmest month• Influenced by both TROPICAL and POLAR air masses

• Most rain results from wave cyclones• Examples: Mediterranean, humid continental, humid sub-tropical (this one is where we are!)

Local Climates:Local conditions also play a role in determining climates.•LARGE LAKES (help to moderate temperatures)•FORESTS (slow down winds and increase humidity)

Cities are MICROCLIMATES and have average temperatures 1-2 degrees HIGHER that the surrounding rural areas. This is due to:

• LESS vegetation in cities• MORE traffic & energy used for heating, lighting, & industry

Cities also get MORE RAIN due to DUST, SMOKE, and POLLUTION creating CONDENSATION NUCLEI necessary for rain to fall.

BIOMES

BIOMESVarious regions of our planet which can best be distinguished by their climate, fauna (animals) and flora (plants) FIVE TYPES:•Desert•Forest•Grassland•Tundra•Aquatic (covered in oceanography)

1. DESERTS•Cover about 1/5 of the planet•Caused by extremely low rainfall•Vegetation consists mainly of low shrubs and small trees (small or no leaves with deep roots)•Animal life is mostly active at night or burrowing with thick skins•Main types of deserts include: ARID, COASTAL, and COLD

2. FORESTS•Cover about 1/3 of the planet and are found across the world•Divided into many types of forests, based on rainfall and temperature•Vegetation is primarily trees•Animal life varies based on the type of forest, but has a wide range of birds, mammals, amphibians and reptiles•Main types of forests include: BOREAL (TAIGA) and TEMPERATE DECIDUOUS (although there are many other variations)

3. GRASSLANDSFound around the globe and serve as grazing areas for large number of animalsUnaltered areas of land where grass is the dominant plant lifeVegetation is primarily grasses. There are a few treesAnimal life consists mostly of grazing animalsMain types of grasslands include: PRAIRIES, STEPPE, and SAVANNA

4. TUNDRA•Coldest of all biomes and is known as the “ice desert” or “frozen prairie”•Located around the North Pole•Little rainfall and soil layer is frozen year-round and is known as PERMAFROST•Vegetation is scarce and mostly consists of shrubs, lichens and mosses•Animal life of mammals adapted to this cold environment with extra layers of fat and the ability to hibernate•Main types include: ARCTIC TUNDRA and ALPINE TUNDRA