UNIT 4 WEATHER DYNAMICS

Transcription

1 UNIT 4 WEATHER DYNAMICS

2 BOOK SECTIONS Chapter 13 Getting started, 13.1, 13.2, 13.3, 13.4, 13.6, 13.8, 13.9, 13.1, 13.13, Chapter 14 Getting started, 14.2, 14.3,14.5, 14.6 Rest of Chapter 14, 15, 16 Class Oral Presentations

3 INTRODUCTION WHY IS A STUDY OF WEATHER IMPORTANT TO OUR LIVES? PLANNING AHEAD (ex: travel, recreational activity, work) SAFETY AND ENGINEERING (ex: creating weather-resistant structures) ECONOMY (ex: careers in meteorology and science) SCIENCE Researching weather patterns and interactions

4 WHAT FACTORS AFFECT OUR WEATHER PATTERNS? GLOBAL Global Warming Ocean Currents Air Masses Seasons/Angle of Sunlight Earth s rotation Latitude Longitude Air Pressure LOCAL Elevation/Topography Proximity to Water Distance Inland Vegetation Cloud Cover

5 SOME GENERAL TERMS WEATHER DYNAMICS is the study of how water and air cause weather patterns. WEATHER The short-range forecast; daily conditions. Ex: temperature, precipitation, wind, humidity, UV CLIMATE Long-term seasonal trends averaged from annual data Ex: In the Atlantic Canada Climate region, winters are cold and summers are Warm

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7 GLOBAL WEATHER PATTERNS 3 MAIN PARTS OF THE EARTH influence GLOBAL WEATHER: ATMOSPHERE AIR HYDROSPHERE WATER LITHOSPHERE/GEOSPHERE LAND

8 SOME GLOBAL WEATHER TERMINOLOGY GEOGRAPHY The study of oceans, continents, countries, ocean currents, and air currents. LONGITUDE Vertical lines on maps/globes that show our position EAST or WEST of the PRIME MERIDIAN line. LATITUDE Horizontal lines on maps/globes that show our position NORTH or SOUTH of the EQUATOR

9 PRIME MERIDIAN, GREENWICH, ENGLAND

10 Some Special Latitude Lines ARCTIC CIRCLE: 66.5 o N, most Northern latitude to receive sun s rays on December 21 st ANTARCTIC CIRCLE: 66.5 o S, most Southern latitude to receive sun s rays on December 21 st TROPIC OF CANCER: 23.5 o N, most Northern latitude to receive sun s vertical rays on June 21 st TROPIC OF CAPRICORN: 23.5 o S, most Northern latitude to receive sun s vertical rays on June 21 st

11 Some Special Latitude Lines... Be able to identify these on a test!

12 Latitude Lines and Seasons On December 21 st, NOTICE how the NORTHERN HEMISPHERE is TILTED AWAY from the SUN (Winter) and the SOUTHERN HEMISPHERE is TILTED TOWARD the SUN (Summer) On JUNE 21 st, NOTICE how the SOUTHERN HEMISPHERE is TILTED AWAY from the SUN (Winter) and the NORTHERN HEMISPHERE is TILTED TOWARD the SUN (Summer)

13 GLOBAL REGIONS POLAR REGION Area between the Arctic Circle Line and North Pole, and Antarctic Circle Line and South Pole MIDLATITUDE REGION Area between the Circle Lines and the Tropics Lines TROPICAL REGION Area between the two Tropics Lines

14 LATITUDE LINES AND GLOBAL REGIONS POLAR REGION MIDLATITUDE REGION TROPICS REGION N POLE ARCTIC CIRCLE TROPIC OF CANCER EQUATOR TROPIC OF CAPRICORN ANTARCTIC CIRCLE S POLE

15 HOMEWORK!!! Questions 1, 2, 4, 8 on page 502!!!

16 HOW IS ENERGY TRANSFERRED? As you already know, all of the earth s energy initially comes from the SUN, with its steamy average temperature of 15,000,000 o C, and its energy output of 3.83 x kj/s.

17 HOW IS ENERGY TRANSFERRED? Weather and climate patterns are based on the transfer of energy between and within air masses and water bodies. 4 METHODS OF ENERGY TRANSFER RADIATION CONDUCTION CONVECTION ADVECTION

18 1. RADIATION The transfer of energy in the form of WAVES. This type of energy can travel through A VACUUM (empty space) as opposed to through a MEDIUM (s, l, g). Examples of radiation waves include: UV, visible light, gamma rays, etc.

19 RADIATION...

20 ELECTROMAGNETIC SPECTRUM The complete set of radiation waves that can travel through empty space. Also See Figure 1 on page 505

21 2. CONDUCTION The transfer of energy through the collision of particles through solids. Occurs in conductive materials (i.e., metals). Small role in weather, bigger role in surface heating.

22 CONDUCTION...

23 3. CONVECTION The transfer of energy by the VERTICAL movement of particles in FLUIDS. Fluids are considered LIQUIDS or GASES. Important for weather patterns.

24 CONVECTION...

25 4. ADVECTION The transfer of energy by the HORIZONTAL movement of particles in fluids. Important for weather patterns. Ex: FOG

26 These forms of heat transfer do not always act alone!

27 THE ALBEDO EFFECT Recall that ALBEDO is an objects ability to reflect LIGHT. LIGHT-coloured objects have a HIGH albedo. DARK-coloured objects have a LOW albedo.

28 HOW MUCH OF THE SUN S ENERGY IS REFLECTED? Refer to Figure 4 on p. 506 of your text. If we count the Sun s energy as starting with 100 %, then: is absorbed by land/oceans is absorbed by clouds is reflected by surface is reflected by clouds

29 HEAT SINK Any object or material that ABSORBS energy and becomes WARMER. A GOOD HEAT SINK is one that heats ups SLOWLY, absorbing a LARGE amount of heat before it heats up, such as WATER. A POOR HEAT SINK increases its temperature QUICKLY when exposed to even a SMALL amount of heat, but it LOSES heat just as quickly, such as what happens with rocks, soil, or sand.

30 HEAT CAPACITY A measure of the amount of heat energy required to raise the temperature of 1 gram of a substance by 1 o C. See Figure 5 on page 506 for a list of some heat capacities. WATER has a high heat capacity, meaning it has to absorb a lot of heat to increase in temperature. METALS has a low heat capacity, meaning it increases temperature with a relatively small addition of heat.

31 HOMEWORK Q. 1, 2, 3, 4, 5, 6, 8 on p. 507.

32 THE EARTH S SEASONS

33 THE EARTH S SEASONS The earth rotates on its axis once a day in a COUNTERCLOCKWISE direction. The earth also orbits around the Sun elliptically and is tilted at an angle of 23.5 o. The earth s orbit around the Sun takes approximately days.

34 THE EARTH S SEASONS Changes in the intensity of the Sun s rays, dues to daily and annual rotations, give us SEASONS. SOLSTICE Points when the poles are tilted at their MAXIMUM toward or away from sun. EQUINOX Sun s rays strike Earth s surface directly at EQUATOR. Day and night of roughly EQUAL length everywhere on earth.

35 THE EARTH S SEASONS SUMMER SOLSTICE Northern hemisphere at MAXIMUM tilt TOWARD sun. (YAY SUMMER!!!) JUNE 21 st is longest day of year. WINTER SOLSTICE Northern hemisphere at MAXIMUM tilt AWAY FROM sun. (BOO WINTER!!!) DEC 21 st is shortest day of year.

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37 THE EARTH S SEASONS VERNAL EQUINOX (SPRING EQUINOX) Marks the first day of SPRING in the Northern Hemisphere (AROUND MARCH 21) AUTUMNAL EQUINOX Marks the first day of FALL in the Northern Hemisphere.(AROUND SEPTEMBER 21)

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39 THE ATMOSPHERE earch?q=layers+of+the+atm osphere&hl=en&emb=0&aq =f#

40 What is the Atmosphere? DEFINITION: The blanket of air and water vapour that surrounds the Earth. If the earth were an ONION, the atmosphere would be like the ONION PEEL. It is about 500 km thick, containing 78% N, 21% O, and some trace elements (ex: CO 2, H 2 O, Ar).

41 LAYERS OF THE ATMOSPHERE Defined according to ALTITUDE, or elevation above sea level. TROPOSPHERE 8-16 km altitude, layer closest to earth s surface This layer is the most dense, meaning it contains the most particles. Weather occurs in this layer. Temperature ranges from 20 to -50degrees Celsius. The tropopause is on the upper end of this layer.

42 LAYERS OF THE ATMOSPHERE STRATOSPHERE km altitude Very dry, temperature average is 10 o degrees Celsius. This layer contains ozone, responsible for absorbing UV radiation from the Sun. Supersonic jets fly in this layer. MESOSPHERE km altitude Temperature average is -75 degrees Celsius.

43 LAYERS OF THE ATMOSPHERE THERMOSPHERE (IONOSPHERE) km altitude Temperature average is 30 o degrees Celsius. Molecules and ions have high energy because they are absorbing powerful waves from the SUN. On earth, we can see the Aurora Borealis in the Northern Hemisphere and the Aurora Australis in the Southern Hemisphere.

44 LAYERS OF THE ATMOSPHERE EXOSPHERE Outer layer converging with SPACE. Thin layer, made up mostly of H and He particles.

45 AURORAS The Sun ejects ionized particles into space that travel to the Earth. Earth s magnetic field deflects these particles toward the poles, creating massive magnetic storms. They vibrate, and when they return to the original state, light is emitted.

46 HOW DOES THE ATMOSPHERE SUPPORT LIFE? 1. Molecules such as O 2, N 2, H 2 O, CO 2 needed to support life processes. 2. Ozone, O 3,needed to absorb harmful UV rays. 3. Water cycle necessary to replenish water in atmosphere, land, and water bodies. 4. Protection from meteors. 5. Maintenance of ideal Temperature. 6. Move energy around the Earth.

47 How did Life Begin?

48 ATMOSPHERIC PRESSURE Defined as the pressure that air particles exert as gravity pulls them toward the centre of the earth Air pressure is greatest at sea level where air is most dense (i.e., thick) Air pressure decreases with altitude. Thus, if you climb a mountain, the weight of the air above you is less, and the pressure is less.

49 PRESSURE GRADIENT Another factor that affects air pressure is whether air is rising or falling. A pressure gradient is a measure of these changes in air pressure over set distance. Pressure gradients can be vertical or horizontal.

50 HORIZONTAL PRESSURE GRADIENTS.. Horizontal pressure gradients. can be shown on a map by joining points of equal atmospheric pressure in concentric circles. They can be used to predict high and low pressure areas and direction and strength of winds. Low wind speed (lines far apart) High Wind speed (lines close together)

51 HOW DO WE MEASURE AIR PRESSURE? Air pressure is measured with an aneroid barometer, ( aneroid meaning without water). Figure 5, p Air pressure is measured in kpa, or kilopascals. 1 kpa = 1000 Pa. If a barometer detects a : low pressure system (less than kpa), this is a sign of poor weather. High pressure system (greater than kpa, this is a sign of good weather.

52 HOW DO WE MEASURE AIR PRESSURE?

53 WINDS Wind is the movement of air in the atmosphere. Some winds are local while others are prevailing. Local winds occur in a fairly small region. Prevailing winds are wind patterns that affect large regions around the world.

54 PREVAILING WINDS In the early 1800s, SAILORS discovered that, in certain areas, the winds blow in the same direction all of the time.

55 THE CORIOLIS EFFECT The change of DIRECTIONof a moving object in a constantly rotating system. The rotation of the EARTH deflects moving air AND water to the RIGHT of its initial direction in the Northern Hemisphere (opposite in the Southern Hemisphere). Note: This direction of deflection is from the viewpoint of the starting position of WHAT IS BEING DEFLECTED (ex: plane, wind, etc.). FIGURE 2 - pg. 517 FIGURE 1 - pg. 525

56 THE CORIOLIS EFFECT ent/visualizations/es1904/es1904page01.cfm

57 THE CORIOLIS EFFECT

58 THE CORIOLIS EFFECT

59 HOMEWORK!!! Page 513, # 7, 8, READ section first, then answer Page 519, # 1, 2, 3, 4.

60 Prevailing Winds in the Northern Hemisphere Prevailing Winds help distribute energy and moisture around the globe. TYPES IN NORTHERN HEMISPHERE Polar Easterlies Cold easterly winds blow from the poles to 60 degrees. Mid-Latitude Westerlies Warm, moist winds blow from the west NEWFOUNDLAND is affected by these. North East Trade Winds Winds that blow toward the equator

61 JET STREAMS Fast moving riversof air that race across the high altitude sky, sometimes at speeds as high as 400 km/h. Jet streams occur about 7000 m up in the upper regions of the troposphere. They consist mostly of westerly winds, and are caused by strong differences in pressure and temperature. Air at the equator is thickerand moves from high to low pressure areas (i.e., N or S of the equator). Jet streams can be thousands of miles long, hundreds of miles wide, but only a mile or so deep.

62 JET STREAMS Pilots can reduce flight time by hitching a ride on a jet stream. Long lines of clouds often indicate the presence of a jet stream.

63 THE HYDROSPHERE Water covers 70 % of the Earth s surface, or 320 million cubic miles. The hydrosphere is all the water that exists on the planet. It includes water in: Oceans Rivers Lakes Aquifers Glaciers/ice Atmosphere

64 WATER DISTRIBUTION 97.5% is salt water, 2.5% is fresh water. Most of our fresh water supply is trapped in polar ice caps (87.3%). Canada is rich in fresh water resources, having 10% of the total world supply.

65 THE HYDROLOGICAL CYCLE Water is cycled through air, land, and water bodies. Important processes that occur in the water cycle include: EVAPORATION: liquid to gas CONDENSATION: gas to liquid TRANSPIRATION: evaporation from leaves SUBLIMATION: solid to gas DEPOSITION: gas to solid INFILTRATION: seep into ground PRECIPITATION: rain, snow, hail, sleet

66 THE HYDROLOGICAL CYCLE

67 MAJOR OCEAN CURRENTS Oceans have a HUGE effect on weather patterns. Here are just a few of the ways water is significant in this regard: Oceans are heat sinks since most of the sun s direct rays hit water. If water is warm, air above it is warm, meaning lots of moisture. If water is cold, air above it is cold. Warm water is constantly moving from the equator to the poles. Cold water is constantly moving from the poles to the equator.

68 MAJOR OCEAN CURRENTS Which ones influence NEWFOUNDLAND weather?

69 NEWFOUNDLAND AND LABRADOR

70 WHAT CAUSES OCEAN CURRENTS? Convection currents Winds across oceans Earth s rotation Shape of continents Heat capacity of Water Amount of salt in oceans

71 FYI Just for FUN In 1992 a container ship in the middle of the Pacific Ocean lost bath tub toys over the side. Rubber duckies started washing ashore all over the west coast of North America. In 1990 in a similar type accident 80,000 pairs of Nike shoes were swept off a Korean ship headed for the United states. Nike shoes started showing up from Hawaii to Oregon and as far north as Alaska. These two accidents provided valuable information to oceanographers regarding ocean currents

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73 P. 524, # 3,4,5 P. 527, # 1, 4, 6 HOMEWORK!!!

74 CLOUDS Clouds are a collection of water droplets that has become dense enough to be visible. Water evaporates and cools as it rises, and condenses into clouds. They are important indicators of weather patterns. Clouds can be grouped according to how they form, how they are shaped, whether or not they will lead to precipitation, and how high they are.

75 3 TYPES OF CLOUD FORMATION 1. CONVECTION CLOUDS 2. OROGRAPHIC CLOUDS 3. FRONTAL CLOUDS

76 1. CONVECTION CLOUDS Convection clouds form when warm air near heated surfaces such as the Earth gain energy from these sources. As this warm air rises in heat, it expands and carries water vapour into the atmosphere. The water vapour cools in the upper atmosphere, forming a convection cloud. These clouds are often puffy.

77 1. CONVECTION CLOUDS Something else puffy!

78 2. OROGRAPHIC CLOUDS Orographic clouds result from warm, moist air ascending up a mountain, forming clouds on the upwind slope as the temperature decreases Thus, the near side of the mountain has precipitation, and the far side of the mountain is often dry.

79 2. OROGRAPHIC CLOUDS wgbh/nova/kilimanj aro/weather.html

80 3. FRONTAL CLOUDS Frontal clouds form when two air masses of different temperatures meet. Warm air masses generally are less dense and contain more moisture than cold air masses, thus rising over, or being pushed upward and over, cold air. The rising air cools and condenses forming a frontal cloud. Where the two air masses meet, this leading edge is called a FRONT.

81 3. FRONTAL CLOUDS

82 3. FRONTAL CLOUDS

83 GROUPS OF CLOUDS BASED ON SHAPE CUMULUS clouds, from a term meaning pile or heap, referring to a TALL CLOUD STRATUS clouds, from stratum, or layer, referring to low-level layered clouds. BASED ON PRECIPITATION NIMBUS clouds, from a term meaning rain, referring to rain-bearing clouds BASED ON ALTITUDE LOW LEVEL: NO PREFIX ( m) MEDIUM LEVEL: ALTO ( m) HIGH LEVEL: CIRRUS ( m)

84 CUMULUS CLOUD VS. STRATUS CLOUD

85 CLOUDS Cumulonimbus

86 FOG Fog is a cloud that forms near the ground. Although there are many different types of fog, it basically forms such that water vapour, as it condenses, attaches itself to little particles such as dust specks. Some types of conditions that cause fog include heat rising from the Earth s surface and cooling rapidly, warm air passing over snow, and warm ocean air meeting cold ocean air.

87 FOG

88 HOMEWORK: P # 2, 4, P # 27 Read and be familiar with Section 13.13, p. 536.

89 WHAT WOULD HAPPEN IF: omy/earthsweather.html

90 AND THAT S ALL FOLKS!!! Fine Print: Now study for your exam!