Water & WeatherApril 4, 2013

SOLs 6.3c, d, e; 6.5a, b, d; 6.6a, b, e, f

Water

Water

Made up of atoms2 Hydrogen and 1 Oxygen atoms bonded together(covalent) to form one molecule of water/compoundTwo forms of gases when bonded together create a water (liquid) molecule

Water

Polar molecule: molecule with electrically charged areas

Hydrogen has a slight positive (+) charge Oxygen has a slight negative (-) chargeLike magnets, the two ends are attracted to each otherAs a polar molecule, a large number

of substances can be dissolved in water = “Universal Solvent”

Water

CohesionWater’s ability to

“stick” to each otherWater molecules are attracted

to other water moleculesThis creates surface tension

Water

Surface TensionThe attraction/pulling between

molecules of water creates a tightness across the surface of water

Allows water strider to glide across the surface of a pond or a paper clip to sit on top

SurfactantA substance that has the ability to break surface tensionSoap, hot water

Water

AdhesionWater’s ability to stick other polar substancesUniversal solvent

Salt-waterSugar-water

If a substance is not polar, it will not dissolve

Oil-waterWax-water

Water

Capillary ActionCohesion and adhesion working together

Water through a strawWater climbing a paper towelWater climbing up a stem of a plant or flowerWater in a graduated cylinder (creates a meniscus)

Gravity plays a role

Water

Three states of matterOnly compound that commonly exists in all three states on Earth (71% of Earth is water)Change between states by adding or taking away heat energySolid water (ice) is less dense than liquid water

Weather

Weather

Definition: condition of Earth’s atmosphere at a particular time and place

WeatherLayers of the Atmosphere

Thin layer wrapped around a large planet

Defined by changes in temperature

TroposphereMost of air

Temperature & pressure decrease with altitude

Virtually all weather takes place here

StratosphereOzone layer collects UV radiation here

Temperature increases

WeatherLayers of the Atmosphere

MesosphereTemperature decreases

Meteors burn up here

ThermosphereLayer is very thin and very hot

ExosphereLayer that transitions into space

WeatherAir

78% Nitrogen (N2)

21% Oxygen (O2)

1% other gasesAlso note that water vapor can be present in the atmosphere from 0 – 4% depending on conditions/location = humidity

WeatherAir

Has mass Contains atoms and moleculesCan be weighed

Has densityThe amount of mass in a given volume of air

Density =

Mass_______Volume

WeatherAir

Has pressureThe amount of force pushing on

an area or surfaceDenser air exerts more pressureMeasured with a barometer in inches or millibarsAffected by altitude

Cold air = more dense, higher pressureWarm air = less dense, lower pressureAir temperature usually measured with a thermometer

WeatherEnergy

Nearly all energy in Earth’s atmosphere comes from the sun in electromagnetic waves called radiationSolar energy combined with water vapor in the air fuels our weather on earth

WeatherEnergy cont.

Incoming solar radiation is in close balance to what leaves the atmosphereHeats our Earth unequally

WeatherEnergy cont.

Greenhouse Effect: natural phenomena that holds some of the sun’s energy to maintain a balance to sustain life on EarthExcess greenhouse gases created by human activity can disrupt the natural balance

WeatherWind

Caused by differences in air pressureMoves from areas of high pressure to areas of low pressureDescribed by direction and speed

Wind direction measured by a wind vaneWind speed measured by an anemometer

WeatherWater

Movement of water between the atmosphere and Earth’s surface is called the water/hydrologic cycleAmount of water on Earth is constantChanges in states of matter: adding and removing of heat energy

WeatherWater

Evaporation: heating of water molecules that changes water from a liquid state to a gaseous state (water vapor)Amount of water vapor in the air = humidityHumidity measured with a hygrometer in percentages

WeatherWater

Condensation: cooling of water vapor that changes the vapor from a gaseous state to a liquid stateTemperature at which condensation begins is called the dew pointWhen water condenses and attaches to other water molecules, dust, and smoke in the air, they form clouds

WeatherWater

CloudsCirrus: wispy, feathery clouds formed at high level when temperatures are very low and made of ice crystalsCumulus: fluffy, rounded piles of cotton that indicate fair weatherStratus: flat layers that are spread out and when they thicken, may produce drizzle, rain, or snow

Fog is a stratus cloud

WeatherWater

Precipitation: any form of water that falls from clouds and reaches Earth’s surfaceCloud droplets or ice crystals must grow heavy enough to fall through the airRain, sleet, hail, and snowRain measured with a rain gauge

WeatherAir Masses

Huge body of air that has similar temperature, humidity, and air pressure throughout it

Tropical: warm air mass formed over tropics with low air pressurePolar: cold air mass

formed above 50° North and below 50° South latitude

Maritime: air mass formed over oceans

Continental: air mass formed over land

WeatherFronts

Area where two air masses meet and do not mix

Cold front: rapidly moving cold air mass runs into a slowly moving warm air mass and the denser cold air pushes up the lighter warm air; narrow band of violent stormsWarm front: moving warm air mass collides with a slowly moving cold air mass and the warm slides over the cold air; high feathery clouds

WeatherStorms

ThunderstormsHeavy rainstorms accompanied by thunder & lighteningWarm air is pushed up rapidly creating an updraft of moist air that forms huge cloudsFormed within large cumulonimbus cloudsAir cools forming droplets and these heavy raindrops create a downdraft of air

TornadoesRapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to touch Earth’s surfaceAlso formed within large cumulonimbus cloudsWind speed and heightWinds as fast as 500km per hour

WeatherStorms

HurricanesTropical, low pressure systems form over warm ocean waters Primarily off the west coast of AfricaUsually begin with when several small thunderstorms come togetherHeat from tropical waters gives the storm energy to spin fasterWinds about 120km per hour or higher

Drought: a water shortage caused by long periods of low precipitation in a particular area

WeatherPredicting Weather

Meteorologists are scientists who study the causes of weather and try to predict itUse several forms of weather instruments and technology to include weather balloons, satellites, and computersWeather Map: graphical “snapshot” of conditions at a particular time over a large area

WeatherPredicting Weather

Weather moves west to east across the United StatesStandard symbols are used on weather maps to show

frontsareas of high and low pressuretypes of precipitationtemperature