weather factors energy in the earth’s atmosphere key concepts: in what forms does energy from the...

Weather Factors Energy in the Earths Atmosphere Key Concepts: In what forms does energy from the sun travel to Earth? What happens to the suns energy when it reaches Earth? Key Terms: Electromagnetic waves Radiation Infrared radiation Ultraviolet radiation Scattering Greenhouse effect

Energy From the Sun You will learn that heat is a major factor in the weather- the movement of heat in the atmosphere causes temperatures to change, winds to blow, and rain to fall. Where does the heat come from? Nearly all energy in the Earths atmosphere come from the sun. This energy travels to Earth as electromagnetic waves, a form of energy that can move through space

Energy From the Sun Radiation is the direct transfer of energy by electromagnetic waves. Most of the energy from the sun travels to Earth in the form of visible light and infrared radiation. A small amount arrives as ultraviolet radiation.

Energy From the Sun Visible light- includes all colors that you see in a rainbow Non-visible radiation- not visible, but can be felt as heat. Sun also gives off ultraviolet radiation. This causes sunburns, can cause skin cancer and eye damage.

Energy in the Atmosphere Before reaching the Earths surface, sunlight must pass through the atmosphere. Some sunlight is absorbed or reflected by the atmosphere before it can reach the surface. The rest passes through the atmosphere to the surface.

Energy in the Atmosphere

Sunlight is absorbed in the atmosphere. The ozone absorbs most of the ultraviolet radiation. Water and carbon dioxide absorb some infrared radiation. Clouds, dust, and other gases absorb energy too. Some sunlight is reflected. Clouds act like mirrors, reflecting sunlight back into space. Dust particles and gases reflect light in all directions, a process called scattering.

Energy in the Atmosphere Scattering: When you look at the sky, the light you see has been scattered by gas molecules in the atmosphere. Gas molecules scatter more short wavelengths of visible light (blue and violet) more than long wavelengths (red and orange). Scattered light therefore looks bluer than sunlight and the daytime sky looks blue When the sun is rising or setting, its light passes through a greater thickness of the atmosphere than when the sun is higher in the sky. More light from blue end of the spectrum is removed by scattering before it reaches your eyes. The remaining light is mostly red and orange light. The sun looks red, and clouds around it become colorful

Energy in the Atmosphere Scattering: sunrise sunset daytime

Energy at Earths Surface Some of the suns energy reaches Earths surface and is reflected back into the atmosphere. About half of the suns energy, however, is absorbed by the land and water and changed into heat. When Earths surface is heated, it radiates most of the energy back into the atmosphere as infrared radiation.

Energy at Earths Surface Much of the infrared radiation cannot travel all the way through the atmosphere back into space. Instead it is absorbed by water vapor, carbon dioxide, methane, and other gases in the air. The energy from the absorbed radiation heats the gases in the air. These gases form a blanket around Earth that holds heat in the atmosphere. The process by which gases hold heat in the air is called the greenhouse effect.

Energy at Earths Surface Greenhouse effect: This is a natural process that keeps Earths atmosphere at a temperature that is comfortable for most living things. Over time, the amount of energy absorbed in the atmosphere and Earths surface is in balance with the amount that is radiated into space. In this way, Earths average temperature remain fairly constant. However, emissions from human activities may be altering this process.

Energy at Earths Surface

Weather Factors Heat Transfer Key Concepts: How is temperature measured? In what three ways is heat transferred? How is heat transferred in the troposphere? Key Terms: Kinetic energy Temperature Thermal energy Thermometer Heat Radiation Conduction Convection Convection currents

You pour a cup of steaming tea into a cup. The cup feels warms to the touch. Somehow, heat was transferred from one object (the cup) to another (your hand) that it was touching. How? We will find out that heat transfer in the troposphere plays an important role in influencing Earths weather.

Thermal Energy and Temperature The tea in the cup and in the teapot are at the same temperature, but have a different amount of total energy. All substances are made up of tiny particles that are constantly moving. The faster the particles are moving, the more energy they have. This energy is called kinetic energy Temperature is the average amount of energy of motion of each particle of a substance. That is it is a measure of how hot or cold something is. Thermal energy is the total energy of motion of in the particles of a substance The hot tea in tea pot has more thermal energy than the hot tea in the cup because it has more particles. http://www.fossweb.com/modulesMS/kit_multimedia/Weatherand Water/matterandenergy/molecules.html http://www.fossweb.com/modulesMS/kit_multimedia/Weatherand Water/matterandenergy/molecules.html

Thermal Energy and Temperature Measuring Temperature: Temperature is one of the most important factors affecting weather. Air temperature is usually measured with a thermometer. A thermometer is a thin glass tube with a bulb on one end that contains a liquid, usually mercury or colored alcohol Thermometers work because liquids expand when they are heated and contract when cooled. As air temperature rises, the temperature of the liquid in the bulb also increase. This causes the liquid to expand and rise up the column.

Thermal Energy and Temperature Temperature Scales: Temperature is measured in units called degrees. The two common temperature scales are the Celsius and Fahrenheit scales. Scientists use the Celsius scale. Freezing point of water is 0*C/ 32*F Boiling point of water is 100*C/212*F

How Heat is Transferred Heat is the transfer of thermal energy from a hotter object to a cooler one. Heat is transferred in three ways: radiation, conduction, and convection. Radiation: If you have ever felt heat from the sun on your face, you are feeling energy coming directly from the sun as radiation. Radiation is the direct transfer of energy by electromagnetic waves. Most of the heat you feel from the sun travels as infrared radiation and cannot be seen, but felt as heat.

How Heat is Transferred Conduction: When you walked barefoot on the hot sand, your felt hot because heat moved directly form the sand into your feet. The direct transfer of heat from one substance to another that it is touching is conduction. When a faster moving sand molecule bumps into a slower- moving molecule, the faster molecule transfers some of its energy The closer together atoms or molecules in a substance are, the more effectively they can conduct heat. Conduction works well in some solid, such as metals, but not as well in liquids and gases. Air and water do not conduct heat very well.

How Heat is Transferred Convection: In fluids (liquids and gases), particles can move easily from one place to another. As the particles move, their energy goes along with them. The transfer of heat by the movement of a fluid is called convection

How Heat is Transferred 3 types of heat transfer:

Heating the Troposphere Radiation, conduction, and convection work together to heat the troposphere. During the day, the suns radiation heats Earths surface. The land becomes warmer than the air. Air near the surface is warmed by both radiation and conduction. (However, heat is not easily transferred from one particle to another by conduction. So only a few meters of the troposphere are heated by conduction.) Thus the air close to the ground is usually warmer than the air a few meters up.

Heating the Troposphere

Radiation, conduction, and convection work together to heat the troposphere. Heat is transferred mostly by convection in the troposphere. When the air near the ground is heated, its particles move more rapidly. As a result they bump into one another and move farther apart. The air becomes less dense. Cooler, denser air sinks toward the surface, forcing the warmer air to rise. The upward movement of warm air and the downward movement of cool air form convection currents. Convection currents move heat throughout the troposphere.

Heating the Troposphere

Weather Factors Winds Key Concepts: What causes winds? How do local winds and global winds differ? Where are the major global wind belts located? Key Terms: Wind Anemometer Wind-chill factor Local winds Sea breeze Land breeze Global winds Coriolis effect Latitude Jet stream

What is Wind? Air is a fluid, and because of that, it can move easily from place to place. Differences in air pressure cause the air to move. A wind is the horizontal movement of air from an area of higher pressure to an area of lower pressure. Winds are caused by differences in air pressure.

What is Wind? Most differences in air pressure are caused by the unequal heating of the atmosphere. Convection currents form when an area of the Earths surface is heated by the suns rays. Air over the heated surface expands and becomes less dense. As the air becomes less dense, its air pressure decreases. If a nearby area is not heated as much, the air above the less-heated area will be cooler and more dense. The cool, dense air with a higher pressures flows underneath the warm, less dense air. This forces the warm air to rise.

What is Wind? Measuring Wind: Winds are described by their direction and speed. Wind direction is determined by a wind vane. The name of a wind tells you where the wind is coming from. Ex. A south wind blows from the south to the north Wind speed can be measured by an anemometer Wind-Chill Factor: When wind blows over your skin and removes body heat. The stronger the wind, the colder you feel. The increased cooling a wind can cause is called wind-chill factor

Local Winds Have you noticed the breeze at the beach on a summer day, if so, you have felt a local wind. Local winds are winds that blow over short distances. Local winds are caused by the unequal heating of Earths surface within a small area. They only form when large-scale winds are weak.

Local Winds Sea Breeze: Unequal heating that occurs along the shore of a large body of water. It takes more energy to heat water than it does an equal part of land. As the Earths surface heats during the day, the land warms up faster. As a result, the air over the land becomes warmer than the air over the water. The warm air expands and rises, creating a low-pressure area. Cool air blows inland from over the water and moves underneath the warm air, causing a sea breeze A sea breeze is a local wind that blows from an ocean or lake.

Local Winds Land Breeze: At night the process is reversed. Land cools more quickly than water, so the air over the land becomes cooler than the air over the water. As the warmer air over the water expands and rises, cooler air from the land moves beneath it. The flow of air from land to a body of water is called a land breeze.

Local Winds

Global Winds Global winds are winds that blow steadily from specific directions over long distances. Like local winds, global winds are caused by the unequal heating of Earths surface. But unlike local winds, global winds occur over a large area.

Global Winds The suns radiation directly hits the equator year round. This causes that area to be intensely warm- tropics The suns rays dont hit as directly at the poles and therefore the surface gets heated less. As a result, temperatures near the poles are much lower than they are near the equator.

Global Convection Currents Global winds develop because of the temperature differences between the equator and the poles. This develops giant convection currents. Warm air rises at the equator and cold air sinks at the poles. Air pressure tends to be lower at the equator and higher at the poles. This difference in pressure causes winds at the surface to blow from the poles to the equator. Higher in the atmosphere, air flows away from the equator towards the poles

Global Convection Currents

The Coriolis Effect If Earth did not rotate, global winds would blow in a straight line from the poles toward the equator. Because Earth is rotating, however, global winds do not follow a straight path. As winds blow, Earth rotates from west to east underneath them, making it seem as if the winds have curved. This is the Coriolis effect.

The Coriolis Effect

Global Wind Belts The Coriolis effect and other factors combine to produce a pattern of calm areas and wind belts around Earth. The major global wind belts are: the trade winds, the polar easterlies, the prevailing westerlies The calm areas are called Doldrums and Horse Latitudes.

Global Wind Belts Doldrums- located near the equator. Here the warm air rises and cooler air moves in and is heated really quickly. There is little horizontal movement, so winds are very weak Horse Latitudes- warm air rising at the equator splits and goes north and south. About 30* north and south latitudes, the air stops moving toward the poles and sinks. This is another area of calm. Historically, sailors would be caught in these areas and ran out of food and water for their horses, so they would throw them overboard. This is how they got their name. A latitude is the distance from the equator measured in degrees.

Global Wind Belts Trade Winds- when the cold air over the horse latitudes sinks, it produces a region of high pressure. This high pressure area causes surface winds to blow both toward and away from the equator. Because of the Coriolis effect, these winds would blow in a specific direction. In the Northern Hemisphere, they generally blow from the northeast and in the Southern Hemisphere, they blow from the southeast. Sailors relied on those winds to move ships carrying goods from Europe to the West Indies and South America- thus they became known as the trade winds.

Global Wind Belts Prevailing Westerlies: between 30* and 60* north and south latitudes, these winds blow toward the poles and turn east due to the Coriolis effect. Because they blow from west to east, they are called prevailing westerlies. These winds play an important role in the weather that we get in the United States.

Global Wind Belts Polar Easterlies: Winds that blow cold air from east to west due to the Coriolis effect near the poles. These winds meet the prevailing westerlies along a region called the polar front. This mixing of warm and cold air along the polar front has a major effect on weather in the United States.

Global Wind Belts

Jet Streams: Located about 10 kilometers above the Earths surface, these are bands of high speed winds Generally blow from west to east at speeds of 200 to 400 km/hr 2 major ones that affect the U.S.- the polar jet stream along northern U.S and the subtropical jet stream that runs along southern U.S. Can fluctuate more north and more south which can affect weather in the U.S. Pilots of airplanes use the jet streams to save time and money on fuel

Global Wind Belts

Wind Map Symbols

Weather Factors Water in the Atmosphere Key Concepts: What is humidity and how is it measured? How do clouds form? What are the three main types of clouds? Key Terms: Water cycle Evaporation Condensation Humidity Relative humidity Psychrometer Condensation Dew point Cirrus Cumulus Stratus

Lets Talk about Water! Vital for all forms of life Covers 70% of Earths surface Of that 96% in oceans- saltwater 1.7 % in groundwater- freshwater 1.7% in glaciers of Antarctica and Greenland-freshwater Small % in other bodies of water on Earth 0.001% in air as water vapor, clouds, and precipitation

Lets Talk about Water! When heat transfers from liquid water, the kinetic energy of the molecules decreases to a very slow movement, they can no longer move past one another. This is a solid state or ice. When energy transfers to ice, kinetic energy increases until the molecules begin to move past one another again, the rigid ice structure is destroyed as the ice melts and water become its liquid state. If more energy is transferred to the liquid water, the kinetic energy increases so much that the molecules escape into the atmosphere as individual molecules as they become a gas. Can exist on Earth in three states: solid, liquid, and gas In order for water to change states, heat must be added or taken away.

Lets Talk about Water!

Can be in the atmosphere or a part of it: Its in the atmosphere when it is a liquid or solid Water is a part of the atmosphere only when it is in the form or water vapor, an invisible gas.

Do you recognize this picture? What do you observe?

As the sun heats the land and oceans, the amount of water in the atmosphere changes. Water is always moving between the atmosphere and Earths surface. The movement of water between the atmosphere and Earths surface is called the Water Cycle. In the water cycle, water moves from oceans, lakes, rivers, and plants into the atmosphere and then falls back to Earth.

Water Cycle 1.Water vapor enters the air by evaporation from the oceans and other bodies of water. Water vapor is also added to the air by living things. Water enters the roots of plants, rises to leaves, and is released as water vapor. Evaporation: the process by which water molecules in liquid water escape into the air as water vapor.

Water Cycle 2. As part of the water cycle, some of the water vapor in the atmosphere condenses to form clouds. 3. Rain and snow fall from the clouds towards the surface. 4. Then water runs off the surface or moves through the ground, back into the lakes, streams, and oceans. Condensation: the process by which molecules of water vapor in the air become liquid water.

Humidity Humidity is a measure of the amount of water vapor in the air. Airs ability to hold water vapor depends on its temperature. Warm air can hold more water vapor than cool air. Why? A psychrometer, a tool to measure humidity.

Humidity In weather reports, we typically hear the term relative humidity when it comes to water vapor. Relative humidity is the percentage of water vapor that is actually in the air compared to the maximum amount of water vapor the air can hold at a particular temperature. For example, at 10*C, 1 cubic meter of air can hold 8 grams of water vapor. If there were actually 8 grams of water vapor in the air, then the relative humidity would be 100%, which is saturated, or full. What about if there were only 4 grams of water vapor in the same area that could hold 8? What is the relative humidity?

Humidity Measuring Relative Humidity: Measured with an instrument called a psychrometer. A psychrometer has 2 thermometers inside, one that is wet and the other that is dry. The wet one has a cloth covering that is moistened with water. A psychrometer is slung or spun and as air blows over the thermometers, the wet one is cooled by evaporation. If humidity is high, the wet bulb water is slow to evaporate. If its low, the water evaporates quickly. Humidity is found by comparing the temperatures between the two bulbs.

Humidity Measuring Relative Humidity:

How Clouds Form When you look at a cloud, you are seeing millions of tiny water droplets or ice crystals. Clouds form when water vapor in the air condenses to form liquid water or ice crystals. Two conditions are required for condensation of the water vapor: The air has to cool There has to be particles in air

How Clouds Form Role of Cooling: We know that cold air holds less water vapor than warm air. As the air cools, the amount of water vapor it can hold decreases. The water vapor condenses into tiny droplets of water or ice crystals. The temperature at which condensation begins is called the dew point. If the dew point is above freezing, the water vapor will form water droplets. If its below freezing, the water vapor turns into ice crystals.

How Clouds Form Role of Particles: For water vapor to condense, tiny particles must be present so the water has something to condense on. In cloud formation, most of these particles are salt crystals, dust from soil, and smoke. Water vapor also condenses onto solid surfaces, such as blades of grass or window panes. Liquid water that condenses from the air is called dew. Ice that has been deposited on a surface is called frost.

How Clouds Form

Types of Clouds Clouds come in many different shapes. Scientists classify clouds into three main types based on their shape: Cirrus Cumulus Stratus Each type of cloud is associated with a different type of weather.

Types of Clouds Cirrus Clouds Wispy, feathery clouds Cirrus comes from the word meaning curl of hair Form only at high levels above 6 km, where temperatures are very low; typically made of ice crystals

Types of Clouds Cumulus Clouds Look like fluffy, rounded piles of cotton Cumulus means heap or mass Form less than 2 km above the ground, but can grow in size and height up to 18 km Low cumulus clouds indicate fair weather Tall ones called cumulonimbus produce thunderstorms Nimbus means rain

Types of Clouds Stratus Clouds: Form in flat layers Strato means spread out Usually cover all or most of the sky and are uniform in dull, gray color May produce drizzle, rain, or snow- called nimbostratus

Types of Clouds Altocumulus and Altostratus: Names of clouds between 2 and 6 km above the ground Alto- means high Middle level clouds Fog: Clouds that form at or near the ground Forms after ground has cooled after a hot, humid day The cold ocean water of San Francisco Bay is often covered by fog in the early morning. What will happen as the sun rises and warms the air?

Types of Clouds

Weather Factors Precipitation Key Concepts: what are the common types of precipitation? How is precipitation measured? Key Terms: Precipitation

In Arica, Chile, the average rainfall is less than 1 millimeter per year. In Hawaii, the average rainfall on Mount Waialeale is 12 meters per year. In Boston, MA, the average rainfall is approximately 1 millimeter. As you can see, rainfall varies greatly around the world.

Global Rainfall

Water evaporates from every water surface on Earth and from living things. But that water eventually returns to Earths surface. Precipitation is any form of water that falls from clouds and reaches Earths surface. Not all clouds produce precipitation. In order for precipitation to occur, cloud droplets or ice crystals must grow heavy enough to fall through the air. In order to do this, some droplets collide and combine to form large droplets. Finally they become heavy enough to drop as raindrops.

Types of Precipitation In warm parts of the world, precipitation is almost always in the form of rain. In colder regions, precipitation may fall as snow or ice. Common types of precipitation include rain, sleet, freezing rain, snow, and hail. Rain- most common type. In order to be called rain, droplets must be a certain size. If they are too small they are called drizzle or mist.

Types of Precipitation Sleet: forms when raindrops fall through a layer of air below 0*C. As they fall, they freeze. Freezing rain: when raindrops fall through cold air near the ground and do not freeze in the air. During ice storms, this can cause smooth thick layers of ice to form on every surface. This can be dangerous.

Types of Precipitation Snow: when water vapor is converted directly into ice crystals called snowflakes. Snowflakes have an endless number of different shapes and patterns. Hail: round pellets of ice larger than 5 mm in diameter are called hailstones. Hail forms only inside cumulonimbus clouds during thunderstorms. Formed by tiny ice pellets being tossed up and down in clouds, growing larger until they are heavy enough to fall.

Types of Precipitation

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