Presentation on theme: "Lesson 1: How Does Uneven Heating of Earth Affect Weather?"— Presentation transcript:
1Lesson 1: How Does Uneven Heating of Earth Affect Weather?
2California Fast Fact!What is unusual about the photo and the month in which it was taken?What clue do the trees give you about the height of the snow?Where and when would you expect to see other scenes like this? Why?Mount Lassen, CaliforniaThis picture was taken in June
3California Fast Fact!The area usually gets about 1m (39in) of snow per month from December to March.Most of this snow melts in the spring and summer.Record snowfalls on the mountain one winter left these GIANT snowdrifts.Mount Lassen, CaliforniaThis picture was taken in June
4CA State Standards4.a – Students know uneven heating of Earth causes air movements (convection currents)4.e – Students know that the Earth’s atmosphere exerts a pressure that decreases with distance above Earth’s surface and that at any point it exerts this pressure equally in all directions.
5Valuable Vocabulary!Atmosphere – The blanket of air surrounding Earth.
6Valuable Vocabulary!Weather – The condition of the atmosphere at a certain place and time.
7Valuable VocabularyAir Pressure – The weight of the atmosphere pushing on a given square unit area of the Earth’s surface.
8Valuable VocabularyConvection Current – The upward and downward movement of air in the atmosphere.
9Valuable VocabularyLocal Wind – Wind that results from local changes in temperature.
10Valuable VocabularyPrevailing Wind – A global wind that blows constantly from the same direction.
11The Atmosphere A blanket of air called the atmosphere surrounds Earth. It is very thin compared to the size of Earth.If Earth were a peach, it would be thinner than the fuzz on the peach!The atmosphere is made up of several layers.1st layer – closest to the Earth’s surface: troposphere
13The AtmosphereThe Troposphere contains about 90% of the atmosphere’s gases.Most of the Earth’s weather happens in the troposphere.Weather is the condition of the atmosphere at a certain place and time.
14The AtmosphereYou can’t see, taste, or touch the air in the atmosphere, but you can feel it.Every time the wind blows, you feel the air.You can feel it because air has mass.Everything on Earth that has mass is pulled toward Earth’s center by gravity.This pull causes air to have weight.Air particles closer to Earth’s surface have more weight than the air higher up.This means that air pressure is greatest at sea level.
15The AtmosphereAir density is another factor that causes air pressure to be greater at sea level.Gravity pulls most of the air in the atmosphere down to the surface.This causes the air closer to Earth’s surface to become much denser, or heavier, than the air farther away from the surface.
16Show What You KnowIn which layer of the atmosphere does most weather occur?
17Show What You KnowIn which layer of the atmosphere does most weather occur?The troposphere is the layer of the atmosphere where most weather occurs.
18Show What You KnowWhat is the relationship between position in the atmosphere and air pressure?
19Show What You KnowWhat is the relationship between position in the atmosphere and air pressure?The lower the position, the higher the air pressure.
20Show What You KnowWrite your own summary of what you learned in class today about the atmosphere.
21SummaryThe earth is covered with a blanket called the atmosphere. The atmosphere is very thin, and is made up of several layers. The layer closest to Earth’s surface is called the troposphere. This layer contains about 90% of of the atmosphere’s gases, and it also is where most of Earth’s weather happens. You can not see, taste or touch air, but you know it is there ever time the wind blows. You can feel air. This is because air has mass. Gravity pulls air particles down, and particles closer to the surface have more weight than the air higher in the atmosphere.
22Air PressureThe higher you go into the atmosphere, the less air there is above you.Air does not only push downwards, but it actually pushes evenly in all directions.Gas molecules are constantly moving in all directions.When you blow up a balloon, the air pressure inside the balloon increases, and it expands in all directions.
23Air Pressure Temperature also affects air pressure. Cold air is denser than warm air.It sinks towards Earth’s surface.The cold air forces warmer, less dense air to rise.As the warm air rises, it begins to cool.Since cold air is denser, it sinks back down to Earth.High Pressure = More dense, cold air sinks.Low Pressure = Less dense, warm air rises.
24Show What You KnowWhat factors affect air pressure?
25Show What You Know What factors affect air pressure? Some factors that affect air pressure are: location in the atmosphere (altitude), temperature, and density.
26Show What You KnowHow does the outside air pressure on the left and right side of a basketball compare?
27Show What You KnowHow does the outside air pressure on the left and right side of a basketball compare?The air pressure is identical on all sides.
28SummarizeSummarize what you learned in class today about air pressure.
29Uneven Heating and Local Winds How did the air feel when you left home this morning?Was it windy, or was it calm?If you were to go outside right now, would the air feel the same?
30Uneven Heating and Local Winds THE BIG IDEA: Air is always moving and changing.When the sun’s energy reaches Earth, some of the energy bounces off objects, such as clouds.Earth absorbs the rest of the energy.Different types of surfaces absorb different amounts of energy.
31Uneven Heating and Local Winds Soil heats up faster and cools off faster than an equal amount of water.During a hot day, soil is hotter than water.It gives off more heat.Because of this, the air over soil tends to be hotter too.Water is cooler than soil, so the air over water tends to be cooler.
32Uneven Heating and Local Winds Cool air is denser than warm air, so it sinks.Air that is warm is less dense, so it is pushed upward by the cooler air, denser air.The upward and downward movement of air is called convection currents.
33Uneven Heating and Local Winds Air in the troposphere moves horizontally.As cool, dense air sinks; it spreads out along the surface.Air at the surface moves from areas of higher pressure to areas of lower pressure.This horizontal movement of air is called wind.
34Uneven Heating and Local Winds Winds can be local, affecting small areas, or global, affecting large parts of the Earth.Sometimes, places in the same general area have slightly different temperatures.This produces local wind, or wind that results from a local difference in temperature.
35Uneven Heating and Local Winds Local winds often occur along lakeshores or seashores.During the day, the air over the land is warmer than the air over the water.The cooler air over the water has a higher pressure than the warmer air over the land.The result is a wind that blows from the water toward the land.This is called a sea breeze.Sea Breeze Explained
36Uneven Heating and Local Winds At night, the wind usually blows in the opposite direction.Land cools off more quickly than water.Once the land becomes cooler than the water, a wind blows from the land toward the water.This is called land breeze.
37Show What You KnowHow does the absorption of energy from the suns rays differ for land and for water?
38Show What You KnowHow does the absorption of energy from the suns rays differ for land and for water?The land absorbs the sun’s energy more quickly than water does.
39Show What You KnowWhat happens to the temperature of the land compared to that of water?
40Show What You KnowWhat happens to the temperature of the land compared to that of water?The land becomes warmer during the day than water does.
41Show What You KnowWhat occurs when cold air sinks?
42Show What You KnowWhat occurs when cold air sinks? What is the horizontal movement of air called?It forces warm air up. The horizontal movement is called wind.
43Show What You KnowWhat is sea breeze? When Does it happen? What causes it?
44Show What You KnowWhat is sea breeze? When Does it happen? What causes it?A sea breeze is a wind from the sea toward the land. During the day, the land warms up faster than the sea. The cooler, denser sea air flows under the warmer air over the land.
45Why is air always moving? Show What You KnowWhy is air always moving?
46Show What You Know Why is air always moving? Earth’s surface is heated unevenly, causing some air to be hotter than other air. Hot air is forced upward by sinking colder air, leading to air movement.
47SummarizeSummarize what you learned in class today about uneven heating of the Earth’s surface.
48Global WindsGlobal winds are prevailing winds that almost always blow from the same direction.Sailors relied heavily on prevailing winds to carry them across the oceans.Uneven heating of Earth’s surface causes prevailing winds.Unlike local winds, prevailing winds result from uneven heating of large parts of Earth’s surface
49Global WindsAn area’s distance from the equator, also known as latitude, affects the amount of heat that the area will receive from the sun.Earth’s poles receive indirect sunlight, or no sunlight at all, so they are always cold.Earth’s equator gets direct sunlight all year, so it’s always warm.As a result, cold air above the poles sinks and moves towards the equator.
50Global Winds Air does not just move in one big circle. Air moves in curved paths, because of Earth’s rotation.This rotation causes prevailing winds.Winds moving north curve to the east.Winds moving south curve to the west.Around the equator this curving causes trade winds to blow from the east.In the United States, this curving causes the prevailing westerlies to blow from the west.
52Global WindsThe prevailing westerlies cause most of the weather systems in the United States to from west to east.This helps forecasters predict the weather, because weather in San Francisco today often moves toward Kansas City tomorrow and then toward Baltimore.
53How does the air in the atmosphere vary with latitude? Show What You KnowHow does the air in the atmosphere vary with latitude?
54How does the air in the atmosphere vary with latitude (distance)? Show What You KnowHow does the air in the atmosphere vary with latitude (distance)?In general, with increases in latitude come decreases in air temperature.
55In what direction do winds that blow toward the poles curve? Show What You KnowIn what direction do winds that blow toward the poles curve?
56In what direction do winds that blow toward the poles curve? Show What You KnowIn what direction do winds that blow toward the poles curve?EASTEASTEASTEASTEASTEAST
57In what direction do winds that blow away from the poles curve? Show What You KnowIn what direction do winds that blow away from the poles curve?
58In what direction do winds that blow away from the poles curve? Show What You KnowIn what direction do winds that blow away from the poles curve?WESTWESTWESTWESTWEST
59Show What You KnowIn what direction do most of the prevailing winds in the United States curve?
60Show What You KnowIn what direction do most of the prevailing winds in the United States curve? Most of the prevailing winds in the United States curve east.
61Why do global winds move in curved paths? Show What You KnowWhy do global winds move in curved paths?
62Show What You KnowWhy do global winds move in curved paths? Earth’s rotation causes winds to curve as they blow northward or southward.
63What two factors cause prevailing winds? Show What You KnowWhat two factors cause prevailing winds?
64Show What You KnowWhat two factors cause prevailing winds? Earth’s rotation and uneven heating of the atmosphere are two factors that cause prevailing winds.
65SummarizeSummarize what you learned in class today about global winds.