Water & Weather April 4, 2013 SOLs 6.3c, d, e; 6.5a, b, d; 6.6a, b, e, f

Water

Water Made up of atoms 2 Hydrogen and 1 Oxygen atoms bonded together(covalent) to form one molecule of water/compound Two 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 (-) charge Like magnets, the two ends are attracted to each other As a polar molecule, a large number of substances can be dissolved in of substances can be dissolved in water = “Universal Solvent” water = “Universal Solvent”

Water Cohesion Water’s ability to “stick” to each other “stick” to each other Water molecules are attracted to other water molecules to other water molecules This creates surface tension

Water Surface Tension The attraction/pulling between molecules of water creates a molecules of water creates a tightness across the surface of water 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 Surfactant A substance that has the ability to break surface tension Soap, hot water

Water Adhesion Water’s ability to stick other polar substances Universal solvent Salt-waterSugar-water If a substance is not polar, it will not dissolve Oil-waterWax-water

Water Capillary Action Cohesion and adhesion working together Water through a straw Water climbing a paper towel Water climbing up a stem of a plant or flower Water in a graduated cylinder (creates a meniscus) Gravity plays a role

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

Weather

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

Weather Layers of the Atmosphere Thin layer wrapped around a large planet Defined by changes in temperature Troposphere Most of air Temperature & pressure decrease with altitude Virtually all weather takes place here Stratosphere Ozone layer collects UV radiation here Temperature increases

Weather Layers of the Atmosphere Mesosphere Temperature decreases Meteors burn up here Thermosphere Layer is very thin and very hot Exosphere Layer that transitions into space

Weather Air 78% Nitrogen (N 2 ) 21% Oxygen (O 2 ) 1% other gases Also note that water vapor can be present in the atmosphere from 0 – 4% depending on conditions/location = humidity

Weather Air Has mass Contains atoms and molecules Can be weighed Has density The amount of mass in a given volume of air Density = Mass Mass _______ Volume

Weather Air Has pressure The amount of force pushing on an area or surface Denser air exerts more pressure Measured with a barometer in inches or millibars Affected by altitude Cold air = more dense, higher pressure Warm air = less dense, lower pressure Air temperature usually measured with a thermometer

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

Weather Energy cont. Incoming solar radiation is in close balance to what leaves the atmosphere Heats our Earth unequally

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

Weather Wind Caused by differences in air pressure Moves from areas of high pressure to areas of low pressure Described by direction and speed Wind direction measured by a wind vane Wind speed measured by an anemometer

Weather Water Movement of water between the atmosphere and Earth’s surface is called the water/hydrologic cycle Amount of water on Earth is constant Changes in states of matter: adding and removing of heat energy

Weather Water 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 = humidity Humidity measured with a hygrometer in percentages

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

Weather WaterClouds Cirrus: wispy, feathery clouds formed at high level when temperatures are very low and made of ice crystals Cumulus: fluffy, rounded piles of cotton that indicate fair weather Stratus: flat layers that are spread out and when they thicken, may produce drizzle, rain, or snow Fog is a stratus cloud

Weather Water Precipitation: any form of water that falls from clouds and reaches Earth’s surface Cloud droplets or ice crystals must grow heavy enough to fall through the air Rain, sleet, hail, and snow Rain measured with a rain gauge

Weather Air 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 pressure Polar: cold air mass formed above 50° North and below 50° South latitude Maritime: air mass formed over oceans Continental: air mass formed over land

Weather Fronts 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 storms Warm front: moving warm air mass collides with a slowly moving cold air mass and the warm slides over the cold air; high feathery clouds

Weather StormsThunderstorms Heavy rainstorms accompanied by thunder & lightening Warm air is pushed up rapidly creating an updraft of moist air that forms huge clouds Formed within large cumulonimbus clouds Air cools forming droplets and these heavy raindrops create a downdraft of air Tornadoes Rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to touch Earth’s surface Also formed within large cumulonimbus clouds Wind speed and height Winds as fast as 500km per hour

Weather StormsHurricanes Tropical, low pressure systems form over warm ocean waters Primarily off the west coast of Africa Usually begin with when several small thunderstorms come together Heat from tropical waters gives the storm energy to spin faster Winds about 120km per hour or higher Drought: a water shortage caused by long periods of low precipitation in a particular area

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

Weather Predicting Weather Weather moves west to east across the United States Standard symbols are used on weather maps to show fronts areas of high and low pressure types of precipitation temperature