Name Period 4 th Six Weeks Notes 2013 Weather

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1 Name Period 4 th Six Weeks Notes 2013 Weather Radiation Convection Currents Winds Jet Streams Energy from the Sun reaches Earth as electromagnetic waves This energy fuels all life on Earth including the water cycle Transfer of heat by the movement of molecules in liquids and gases How it works: Radiant energy from the Sun is absorbed by the Earth s atmosphere & oceans As fluids heat, molecules move faster and expand The hotter and less dense materials rise The cooler and more dense materials sink Then the process repeats Occur within Earth s atmosphere and oceans This process creates Earth s wind and ocean currents Movements of large masses of air across Earth s surface Global Winds Caused by the uneven heating of Earth s surface at the equator versus the poles & by the rotation of the Earth Warm air rises at the equator and moves toward the poles Cooler air sinks at the poles and moves toward the equator Named for the direction they come from Ex. Westerlies blow from West to East Affect climate & weather all over the Earth Local Winds only found along the coasts of continents During the day, land warms more rapidly than the water Air above land warms, becomes thinner & rises drawing cooler air in from the sea At night the process reverses & the cooler air flows out to sea Narrow streams of high speed wind (100+mph) flowing high in the atmosphere (~30,000 ft.) Move west to east

2 Coriolis Effect Ocean Surface Currents Air Masses The rotation of Earth causes wind & ocean currents to follow a curved path Currents flow clockwise in the Northern hemisphere Currents flow counterclockwise in the Southern hemisphere Caused by global winds pushing along the surface of the oceans Affect climates of nearby continents Warm currents are usually found near areas with tropical or subtropical climates Cold currents are usually found near areas with temperate or subarctic climates Large volume of air defined by its temperature & moisture content Continental air masses form over land and are DRY Maritime air masses form over water and are MOIST Polar air masses are COLD Tropical air masses are WARM Fronts Cold Fronts Boundary between two air masses of different temperature Colder air mass forces the warm, moist air to rise forming rain clouds Move fast causing violent storms followed by fair, cooler weather Warm Fronts Warmer air mass overtakes the colder air mass & slowly forms rain clouds Move slow causing light rain & showers followed by warmer, more humid weather Stationary Fronts Boundary between two different air masses, neither of which are strong enough to replace the other Causes light scattered showers for several days or until another front moves in and pushes it out of the way

3 Air Pressure High Pressure H Low Pressure L Molecules in Earth s atmosphere constantly bounce off each other and everything else around them. The force exerted by these molecules is called air pressure Air particles ALWAYS move from areas of high pressure to low pressure Molecules that are cooler have less energy They move very slowly and stay close together This makes cooler air masses MORE dense than warmer ones The denser air RISES and prevents clouds from forming High pressure areas are usually found far from front boundaries They are associated with clear, sunny skies & good weather ( happy highs ) Molecules that are warmer have more energy They move more rapidly and spread far apart This makes warmer air masses LESS dense than colder ones The less dense air RISES and forms clouds Low pressure areas are usually found along front boundaries They are associated with cloudy skies & bad weather ( lousy lows ) Weather Maps Weather Station Models Hurricanes A massive storm system with a low pressure center surrounded by a spiral of thunderstorms that produce strong winds and heavy rain Develop throughout the summer and fall Form over the warm tropical waters near the equator

4 Earth s Movement Moon The Earth s axis is the imaginary line through Earth from the North geographic pole to the South geographic pole The spinning of Earth on its axis is called rotation This causes Earth to experience day and night As it rotates on its axis each day, Earth also moves along a path around the Sun This is a revolution One revolution takes 365 ¼ days Earth is a satellite of the Sun, moving around it in a path called an orbit Lunar Cycle You see the Moon because it reflects sunlight IT DOES NOT PRODUCE LIGHT!!! As the Moon revolves round the Earth, the Sun always lights one half of it However, we do not always see the entire lighted part of the Moon What you see are moon phases or different portions of the lighted parts

5 Moon s Movement The Moon rotates on its axis every 27.3 days and revolves (orbits) around the Earth every 27.3 days Since rotation and revolution length are the same, we always see the same side of the Moon Waxing Waning New Moon Waxing Crescent First Quarter Waxing Gibbous Full Moon Waning Gibbous Third Quarter Waning Crescent Light on the right (LOR-WAX) Light on the left (LOL-WANE) To gradually increase in size Portion of the lighted half we can see is increasing To gradually decrease in size Portion of the lighted half we can see is decreasing The Moon s unlit half is facing the Earth None of the lighted half is visible Only a small amount or crescent of the Moon s lighted half is visible The amount of visibility is increasing or waxing Exactly ½ of the Moon s lighted half is visible The Moon is ¼ (one-quarter) of the way through its revolution around the Earth A large amount or gibbous of the Moon s lighted half is visible The amount of visibility is still increasing or waxing All or full amount of the Moon s lighted half is visible The moon is ½ of the way through its revolution around the Earth A large amount or gibbous of the Moon s lighted half is visible The amount of visibility is now decreasing or waning Exactly ½ of the Moon s lighted half is visible again The Moon is ¾ (three-quarters) of the way through its revolution around the Earth Only a small amount or crescent of the Moon s lighted half is visible again The amount of visibility is still decreasing or waning Once no light is visible again, the cycle repeats

6 Seasons Earth s tilt, along with its elliptical orbit, gives us our seasons The distance from the Earth to the Sun DOES NOT cause the seasons PROOF Earth is actually FARTHER AWAY from the Sun during the Northern hemisphere s summer and CLOSER in the winter Seasons As the Earth orbits the Sun, the Northern hemisphere is at various times pointed more toward and more away from the Sun This is also true for the Southern hemisphere, but at opposite times of year NOTICE the Earth DOES NOT tilt back and forth!! It is ALWAYS tilted in the same direction!! Northern Spring Southern Fall Northern Summer Southern Winter Northern Winter Southern Summer Northern Fall Southern Spring

7 Solstice Two times during the year, the Sun s rays reach the greatest distance North or South of the equator and are directly over the Tropic of Cancer or Tropic of Capricorn Summer solstice or the longest day of the year occurs on June 21 or 22 Winter solstice or the shortest day of the year occurs on December 21 or 22 These dates are OPPOSITE in the Southern hemisphere Equinox During an equinox, the Sun s rays hit directly on Earth s equator The lengths of day and night are nearly equal all over the world In the Northern Hemisphere, spring equinox is March 21 or 22 and fall equinox is September 21 or 22 The dates are opposite for the Southern hemisphere

8 Tides High Tide Low Tide Spring Tide Tides The daily rise and fall of the ocean water level Controlled by the gravity between moon and Earth Moon s gravity pulls ocean water away from Earth s surface creating a tidal bulge Two high and low tides occur in a location every day Caused by daily rotation of Earth on its axis Occur on the side of the Earth where the tide is bulging Occur on the side of the Earth that is in between the tidal bulges Occurs twice a month during new moon and full moon when the Moon is in a straight line with the Earth and Sun Greatest difference between high and low tides Neap Tide Occurs twice a month during 1st and 3rd quarter moon when Sun and moon pull at right angles to the Earth Lowest difference between high and low tides