Presentation is loading. Please wait.

Presentation is loading. Please wait.

Earth Science Chapter 16 and 17 Weather and Climate.

Similar presentations

Presentation on theme: "Earth Science Chapter 16 and 17 Weather and Climate."— Presentation transcript:

1 Earth Science Chapter 16 and 17 Weather and Climate

2 Goal l Prediction l Old way –Groundhog –Color of the sky l Modern way –satellites –instruments –computers

3 Weather Factors l Studied by meteorologists l Several factors influence the weather l Heat energy l air pressure l winds l moisture

4 Heat Energy l Almost all the earths energy comes from the sun l Visible and invisible waves –Infrared and ultraviolet l As light hits the earth –some is reflected back into space by dust particles and water droplets –Some is absorbed in the atmosphere, in the ozone layer

5 Heat Energy l Ozone layer protects us from dangerous ultraviolet radiation. l The energy that does hit the earth is converted to heat energy. l Heat is then spread through the atmosphere –Conduction –Convection –Radiation

6 Conduction l Direct transfer of heat l From one molecule to the next l Air above the pavement is slightly hotter. l Not a big effect on the atmosphere

7 Convection l Transfer of heat in a fluid l Heated air is less dense, it rises l Cooler air is more dense, it sinks l Makes convection currents in the atmosphere l Circular movement of air caused by uneven heating. l Big impact on the atmosphere

8 Radiation l Transfer by waves l Energy transferred by infrared waves. l Infrared waves get trapped by carbon dioxide and other gases in the atmosphere l Called the greenhouse effect. l If there is too much carbon dioxide, the earth will warm up l affect the worlds weather

9 Variations of temperature l Why are the tropics hot, and the poles cold? l The angle of the suns rays. l Near 90 at the equator l Becomes smaller as you get farther from equator closer to the poles


11 Measuring temperature l Device is called a thermometer l As the temperature rises, liquid inside the bulb expands and rises up the thin tube. l Units are called degrees l Scientist use the Celsius scale l Water boils at 100 C l Water freezes at 0 C l Body temperature is 37 C

12 Air Pressure l Caused by air molecules hitting you. l We are at the bottom of a sea of air l We can feel the pressure of all that air above us l Dense air has more mass, so it causes a higher pressure l Three factors that influence air density and air pressure

13 Temperature l Air expands as it is heated. l Higher temperature l lower density l less pressure

14 Water Vapor l Water molecules have less mass than air molecules. l More water vapor l less mass l lower density l Less pressure l Moist air has lower pressure than dense air

15 Elevation l Higher elevations air is thinner l fewer air molecules above l less dense l lower pressure. l We need to set a standard l Measure 1 atmosphere at 0 C at sea level

16 Barometer lAt one atmosphere pressure a column of mercury 760 mm high. Dish of Mercury Column of Mercury

17 Another barometer l An aneroid barometer l Airtight metal container l When the pressure changes, it expands or contracts and moves a needle.

18 Wind l The movement of air l Caused by warm air rising, less dense, lower pressure l Cooler air sinking, more dense, higher pressure l Cooler air moves under warmer air. l Two types of winds –local –global

19 Local Wind l Blow from any direction, over short distances l Sea breeze l During the day, land heats up faster l Warm air over land rises. l Cool air from over ocean or lake replaces l Air blows from the sea, called a sea breeze

20 Land Breeze l During night l Land cools off faster l Warmer air over sea rises l Cooler air from the land replaces it l Wind is from land, called a land breeze l Winds are named by the direction they come from. l A northern wind comes from the north

21 Monsoon l A major land or sea breeze l a seasonal wind l One part of the year the wind blows from the continent to the ocean l The rest of the year it blows from the ocean to the continent. l Makes for two seasons, rainy and dry

22 Global Winds l Caused by unequal heating l Near the equator air is hot l At the poles it is cold l Air moves from the poles to the equator l Not directly north or south, because the earth rotates.

23 Coriolis Effect l Apparent shift (or curve) in movement caused by the rotation of the earth l In the Northern Hemisphere they curve to the right l In the Southern Hemisphere they curve to the left.



26 Global Winds l Doldrums- l At the equator the winds are calm l Caused by rising, low pressure, warm air l Problem for sailors l Horse latitudes- at 30 Latitude air from the equator cools and sinks l air is calm here

27 Horse Latitudes Doldrums

28 Global Winds l Trade winds l Some sinking air moves towards the equator l Makes steady winds from the east in the Northern hemisphere l From the east in the Southern Hemisphere l Usually weak winds

29 Global Winds Trade Winds

30 Global winds l Sinking air moves toward pole 40 to 60 l Bends to right in Northern Hemisphere l goes east l Prevailing Westerlies l Why our weather moves to east l Bends to left in Southern Hemisphere l goes east

31 Global Winds l Used by sailors to the New World and back

32 Global Winds l North and south of 60 the air flows from the poles then rises. l Turn right in the Northern Hemisphere l Polar Easterlies l Turn left in the Southern Hemisphere l Cold weak winds l Local winds may be different than global winds

33 Jet Streams l Not Discovered until the 1940s l High Pressure belts of air high in the atmosphere l Move from west to east at 180 to 350 kilometers per hour l Wander as they circulate l Can move weather systems

34 Measuring wind l Use wind vane to measure direction l An anemometer to measure wind speed. l Rotating cups l Faster rotation, higher wind speed

35 Moisture l Water vapor in the atmosphere is called humidity, l Comes from evaporation from oceans, lakes, rivers, soil, plants, animals l Varies from place to place l Higher temperature air can hold more moisture

36 Relative Humidity l Comparing how much water vapor there is in the atmosphere to how much it could possibly hold. l Given as a percentage. l At 100% the air is saturated l As warm air is cooled, it can hold less, so it condenses out. l The temperature that water condenses out is called the dew point.

37 Clouds l Form when moisture condenses on small particles of dust. l Clouds are tiny water droplets. l Categorized two ways l Shape l Altitude

38 Shape l Cumulus - puffy, flat bottom good weather l Can turn into cumulonimbus clouds which produce thunderstorms. l Stratus- layer clouds, grey, light rain l Close to ground called fog l Turn into Nimbostratus which bring rain or snow

39 Shape l Cirrus- Feather clouds at high altitudes l Ice crystals l Appear when the weather is clear but often are followed by rain or snow

40 Altitiude l Stratus- Low level <2.5 km l Cumulus- Mid level 2-6 km l Cirrus- high level Higher than 6-12 km l Cumulonimbus clouds can rise to heights of 13 km

41 Cirrus

42 Cirrostratus

43 Cirrocumulus

44 Altocumulus

45 Stratus

46 Stratocumulus

47 Cumulus

48 Cumulonimbus

49 Precipitation l Caused by water condensing in the clouds and falling to earth l Water droplets must get bigger to fall l Combine with other droplets l Raindrops are 1 million times bigger than cloud droplets l Gravity pulls them to earth l Sleet- rain freezes as it falls to earth

50 Other types l Snow- moisture forms ice crystals as it condenses l Hail- chunks of ice formed in an updraft –Ice crystals form –falls through moisture –Wind blows it back up –Freezes and falls again –Repeats –Layers, up to 5 inches across

51 Measuring Precipitation l Use a rain gauge l Straight sided, flat bottom container that fills up with water

52 Weather Patterns l Weather is caused by large air masses l Areas with the same temperature and humidity l Continental- dry - low humidity l Maritime - wet - high humidity l Polar- cold l Tropical- hot l Four possibilities

53 Maritime Polar l Forms over cold water l Causes fog in California

54 Maritime Tropical l Forms over warm water l Hot humid days

55 Continental tropical l Forms over Mexico l Dry hot air to Southwest

56 Continental Polar l Forms over Canada l Very cold winter days

57 Fronts l Where two air masses meet l Cold front when cold air replaces warm air l Warm front when warm air replaces cold air l Occluded front- when a cold front catches up with a warm front l Stationary front- no movement occurs when cold and warm air meet.

58 Cold Front l Warm air rising cause violent thunderstorms l Clear cool days follow Cold Air Warm Air

59 Warm Front Cold Air Warm Air

60 Warm Front l Rain and showers are caused by warm fronts l Followed by hot humid days

61 Occluded Front Cold Air Warm Air Cold Air

62 Occluded Front l Less violent weather than a cold front.

63 Stationary Front l Cold air meets warm air and no movement occurs l Rain can fall in the same place for days

64 Symbols Cold Front Warm Front Occluded Front Stationary Front







71 Weather from Fronts l Warm fronts form nimbostratus clouds l Cause steady rainfall that lasts for hours l or snow l Cold fronts can form cumulonimbus l Produce thunderstorms and hail

72 Cyclones l An area of low pressure. l Warm air is rising l Wind spins around counter clockwise in the Southern Hemisphere l Cause stormy rainy weather

73 Anticyclones l High pressure area l cold air sinks and spirals outward l Move in a clockwise direction in the Northern Hemisphere l Usually bring clear dry weather

74 Reading Maps

75 Clear Cloudy Partly Cloudy West Wind East Wind

76 Hurricanes l A powerful cyclone l Forms over tropical oceans l Late summer or early fall l Warm moist air rises l Starts to spin, then spins faster l Forms a cylinder of strong winds around the center, which is calm l Called the eye

77 Hurricanes l Wind speeds reach 120 to 320 km/hr l Lose energy when they hit land, but heavy rains and large waves cause damage l This year expect 21 named storms l 1 or 2 major

78 Tornadoes l Whirling funnel shaped cloud l Develops inn cumulonimbus clouds l In the center of the funnel there is low pressure, which acts like a vacuum cleaner l Tornadoes over water are called water spouts l Winds can reach speeds of 350 km/hr

79 Predicting Weather l Allows people to plan their days l Warns people of severe weather l Meteorologists interpret weather information from a variety of sources –observers –balloons –satellites –weather stations around the world

80 Predicting Weather l Draw a weather map l use the symbols we have studied l Add curved lines called isotherms which connect areas with the same temperature l Other curved lines called isobars connect areas with the same pressure

81 Controlling the Weather l Could save money and lives l Only success has come from seeding clouds l Sprinkling dry ice to condense moisture l or silver iodide to cool clouds enough to form crystals l Used to remove fog around airports l Or tried to increase the snow pack in the Sierras

Download ppt "Earth Science Chapter 16 and 17 Weather and Climate."

Similar presentations

Ads by Google