Weather Factors Energy in the Earth’s Atmosphere Key Concepts: In what forms does energy from the...
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Weather Factors Energy in the Earth’s Atmosphere Key Concepts: In what forms does energy from the sun travel to Earth? What happens to the sun’s energy
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
Slide 2
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
Slide 3
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.
Slide 4
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.
Slide 5
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.
Slide 6
Energy in the Atmosphere
Slide 7
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.
Slide 8
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
Slide 9
Energy in the Atmosphere Scattering: sunrise sunset
daytime
Slide 10
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.
Slide 11
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.
Slide 12
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.
Slide 13
Energy at Earths Surface
Slide 14
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
Slide 15
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.
Slide 16
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.
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Water/matterandenergy/molecules.html
Slide 17
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.
Slide 18
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
Slide 19
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.
Slide 20
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.
Slide 21
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
Slide 22
How Heat is Transferred 3 types of heat transfer:
Slide 23
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.
Slide 24
Heating the Troposphere
Slide 25
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.
Slide 26
Heating the Troposphere
Slide 27
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
Slide 28
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.
Slide 29
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.
Slide 30
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
Slide 31
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.
Slide 32
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.
Slide 33
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.
Slide 34
Local Winds
Slide 35
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.
Slide 36
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.
Slide 37
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
Slide 38
Global Convection Currents
Slide 39
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.
Slide 40
The Coriolis Effect
Slide 41
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.
Slide 42
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.
Slide 43
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.
Slide 44
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.
Slide 45
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.
Slide 46
Global Wind Belts
Slide 47
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
Slide 48
Global Wind Belts
Slide 49
Wind Map Symbols
Slide 50
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
Slide 51
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
Slide 52
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.
Slide 53
Lets Talk about Water!
Slide 54
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.
Slide 55
Do you recognize this picture? What do you observe?
Slide 56
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.
Slide 57
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.
Slide 58
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.
Slide 59
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.
Slide 60
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?
Slide 61
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.
Slide 62
Humidity Measuring Relative Humidity:
Slide 63
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
Slide 64
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.
Slide 65
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.
Slide 66
How Clouds Form
Slide 67
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.
Slide 68
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
Slide 69
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
Slide 70
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
Slide 71
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?
Slide 72
Types of Clouds
Slide 73
Weather Factors Precipitation Key Concepts: what are the common
types of precipitation? How is precipitation measured? Key Terms:
Precipitation
Slide 74
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.
Slide 75
Global Rainfall
Slide 76
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.
Slide 77
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.
Slide 78
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.
Slide 79
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.