Chapter 2 – Weather factors 2.1 Energy in the Atmosphere.

Chapter 2 – Weather Chapter 2 – Weather factorsfactors

2.1 Energy in the Atmosphere2.1 Energy in the Atmosphere

Think about it…Think about it…

•Where does the energy of our Where does the energy of our Earth come from?Earth come from?

Electromagnetic RadiationElectromagnetic Radiation

•Nearly all of the energy in Earth’s Nearly all of the energy in Earth’s atmosphere comes from the atmosphere comes from the sunsun

• Energy travels as electromagnetic Energy travels as electromagnetic waves.waves.

• Electromagnetic waves are a form of Electromagnetic waves are a form of energy that can move through the energy that can move through the vacuum of space.vacuum of space.

• Electromagnetic waves are Electromagnetic waves are classified by their classified by their wavelengthswavelengths

Electromagnetic RadiationElectromagnetic Radiation

•The direct transfer of energy by The direct transfer of energy by electromagnetic waves is called electromagnetic waves is called radiation.radiation.

•Most energy from the sun Most energy from the sun reaches the Earth in the form of reaches the Earth in the form of infrared radiation, visible lightinfrared radiation, visible light, , and and ultraviolet radiationultraviolet radiation..

Wavelengths Wavelengths

Analyze the picture …Analyze the picture …take 1 minute take 1 minute and discuss with a partner…and discuss with a partner…

• Why do we see different colors?Why do we see different colors?

• How do color and wavelength compare?How do color and wavelength compare?

• Which colors have the shortest wavelengths?Which colors have the shortest wavelengths?

• Which colors have the longest wavelengths?Which colors have the longest wavelengths?• What type of radiation has wavelengths that What type of radiation has wavelengths that

are shorter than visible light? Longer?are shorter than visible light? Longer?

Were you right?Were you right?• Why do we see different colors? Why do we see different colors? Because Because

of different wavelengthsof different wavelengths• How do color and wavelength compare? How do color and wavelength compare?

Short and long wavelengths result in Short and long wavelengths result in different colors different colors

• Which colors have the shortest Which colors have the shortest wavelengths? wavelengths? Blue and VioletBlue and Violet

• Which colors have the longest Which colors have the longest wavelengths? wavelengths? Red and orangeRed and orange

• What type of radiation has wavelengths What type of radiation has wavelengths that are shorter than visible light? Longer? that are shorter than visible light? Longer? Ultraviolet radiation, x-rays and gamma Ultraviolet radiation, x-rays and gamma rays / infrared radiation and radio wavesrays / infrared radiation and radio waves

Visible Light: ROY G BIVVisible Light: ROY G BIV• Infrared RadiationInfrared Radiation – wavelengths are – wavelengths are

longer than red light.longer than red light.

• The color of visible light with the longest The color of visible light with the longest wavelength is wavelength is Red.Red.

• The color of visible light with the shortest The color of visible light with the shortest wavelength is wavelength is Blue.Blue.

• Ultra-violet RadiationUltra-violet Radiation – wavelengths are – wavelengths are shorter than violet light shorter than violet light

Think about it…Think about it…

•What role does our atmosphere What role does our atmosphere play in the ability of energy to play in the ability of energy to reach our Earth?reach our Earth?

Energy Energy

• Water Vapor and Carbon Dioxide absorb some Water Vapor and Carbon Dioxide absorb some infrared radiationinfrared radiation

• Some of the sun’s rays are Some of the sun’s rays are reflectedreflected by clouds, by clouds, dust, and molecules of gases dust, and molecules of gases called scattering.called scattering.

• Gas molecules scatter short wavelengths of Gas molecules scatter short wavelengths of blue and violet more than red and orange blue and violet more than red and orange making the daytime sky look blue.making the daytime sky look blue.

EnergyEnergy

• The ozone layer absorbs most of the ultraviolet The ozone layer absorbs most of the ultraviolet radiationradiation

• Green house effect- natural process by which Green house effect- natural process by which gas holds heat in the air. gas holds heat in the air.

• Gases include water vapor, carbon dioxide, Gases include water vapor, carbon dioxide, methane, and other gases that form a blanket methane, and other gases that form a blanket around earth.around earth.

• Some energy reaches the surface and warms Some energy reaches the surface and warms the land and waterthe land and water

Energy in the atmosphereEnergy in the atmosphere

What are your thoughts?What are your thoughts?

•What might conditions on What might conditions on Earth be like without the Earth be like without the Greenhouse effect?Greenhouse effect?

Chapter 2 – Weather Chapter 2 – Weather factorsfactors

2.2 Heat Transfer2.2 Heat Transfer

Energy and Temperature Energy and Temperature

• Thermal energy is the total energy Thermal energy is the total energy of MOTION of the molecules in a of MOTION of the molecules in a substance.substance.

• Temperature is an average amount Temperature is an average amount of energy of motion of the of energy of motion of the molecules in a substance.molecules in a substance.

Hot = fast moving moleculesHot = fast moving moleculesCold = slow moving moleculesCold = slow moving molecules

Measuring Temperature Measuring Temperature

• Thermometers are used to measure Thermometers are used to measure temperaturetemperature

• Liquids expand when they are heated Liquids expand when they are heated and contract when they are cooledand contract when they are cooled

• Temperature is measured in units Temperature is measured in units called degrees. (Celsius or Fahrenheit)called degrees. (Celsius or Fahrenheit)

• Water freezes at 0ºC and boils at Water freezes at 0ºC and boils at 100ºC100ºC

How Heat is TransferredHow Heat is Transferred

• Heat is the energy transferred from a Heat is the energy transferred from a hotter object to a cooler one. hotter object to a cooler one.

Heat is transferred 3 ways Heat is transferred 3 ways • Radiation is the direct transfer of Radiation is the direct transfer of

energy by electromagnetic waves.energy by electromagnetic waves.

ex) feeling the warmth of the ex) feeling the warmth of the fire on your skinfire on your skin

Heat is transferred 3 waysHeat is transferred 3 ways

• Conduction is the direct transfer of Conduction is the direct transfer of heat from one substance to another heat from one substance to another substance ( must be touching)substance ( must be touching)

Heat is transferred 3 waysHeat is transferred 3 ways• Convection is the transfer of heat by Convection is the transfer of heat by

the movement of a fluid.the movement of a fluid.

ex) heating up soup in a pan.ex) heating up soup in a pan.

Heat Transfer in the Heat Transfer in the Troposphere Troposphere

A comparison…A comparison…

Chapter 2 - Weather factorsChapter 2 - Weather factors

2.3 Winds2.3 Winds

What Causes Winds?What Causes Winds?

• Wind is the horizontal movement of air Wind is the horizontal movement of air from an area of high pressure to an from an area of high pressure to an area of lower pressure.area of lower pressure.

• All winds are caused by differences in All winds are caused by differences in air pressure.air pressure.

• Differences in air pressure are caused Differences in air pressure are caused by unequal heating of the atmosphere. by unequal heating of the atmosphere.

Measuring WindMeasuring Wind

• Wind vanes are used to determine wind Wind vanes are used to determine wind direction.direction.

• The name of a wind tells you where the wind The name of a wind tells you where the wind is coming from. is coming from.

• Anemometers are used to measure wind Anemometers are used to measure wind speed.speed.

• Wind over your skin removes body heat.Wind over your skin removes body heat.

• The increased cooling that a wind can cause The increased cooling that a wind can cause is called is called

the wind- chill factorthe wind- chill factor..

Local WindsLocal Winds

• Winds that blow over short distances.Winds that blow over short distances.

• Caused by unequal heating of Earth’s Caused by unequal heating of Earth’s surface within a small area.surface within a small area.

• Usually occurs near a body of water.Usually occurs near a body of water.

Local WindsLocal Winds• Land heats up faster during the day, warming the Land heats up faster during the day, warming the

air above it. Warm air expands and rises, creating air above it. Warm air expands and rises, creating a low-pressure area. Cool air blows inland from a low-pressure area. Cool air blows inland from

the water tothe water to replace the warm air.replace the warm air.

Local WindsLocal Winds• sea breezesea breeze – a wind that blows FROM – a wind that blows FROM

an ocean or a lake onto landan ocean or a lake onto land

• land breezeland breeze – the flow of air FROM – the flow of air FROM land to a body of waterland to a body of water

MonsoonsMonsoons

• Sea and land breezes over a large Sea and land breezes over a large region that change direction with the region that change direction with the seasonsseasons

Global WindsGlobal Winds

• Winds that blow steadily from specific Winds that blow steadily from specific directions over large distances.directions over large distances.

• Caused by unequal heating of Earth’s Caused by unequal heating of Earth’s surface. (equator vs. poles)surface. (equator vs. poles)

• Global Convection Currents cause Global Convection Currents cause wind at Earth’s surface to blow from wind at Earth’s surface to blow from the poles to the equator.the poles to the equator.

• Higher in the atmosphere, air flows Higher in the atmosphere, air flows away from the equator and toward the away from the equator and toward the poles.poles.

Global WindsGlobal Winds

• The movement of air between the equator and The movement of air between the equator and the poles produces global winds.the poles produces global winds.

• Coriolis Effect – winds do not blow in straight Coriolis Effect – winds do not blow in straight lines because the Earth is spinning underneath lines because the Earth is spinning underneath them. This causes the winds to curve.them. This causes the winds to curve.

• In the NORTHERN HEMISPHERE – the Coriolis In the NORTHERN HEMISPHERE – the Coriolis Effect causes our wind to turn towards the Effect causes our wind to turn towards the right. It is the opposite in the southern right. It is the opposite in the southern hemisphere.hemisphere.

Jet StreamJet Stream

• Bands of high-speed wind about Bands of high-speed wind about 10km above Earth’s surface. 10km above Earth’s surface.

• They blow from west to east at about They blow from west to east at about 200-400 km per hour200-400 km per hour

Global Wind BeltsGlobal Wind Belts

• DOLDRUMS: DOLDRUMS:

•Caused by rapid warming of airCaused by rapid warming of air

•near the equatornear the equator

•air is almost always warm so air is almost always warm so there are little to no windsthere are little to no winds

Global Wind BeltsGlobal Wind Belts

• HORSE LATITUDES:HORSE LATITUDES:•Caused when air from equator stops Caused when air from equator stops moving towards poles and sinksmoving towards poles and sinks

•Latitude is the distance from the Latitude is the distance from the equator, measured in degreesequator, measured in degrees

•30º north and south latitudes, Calm 30º north and south latitudes, Calm airair

Global Wind BeltsGlobal Wind Belts

• TRADE WINDS:TRADE WINDS:

•Caused when cold air over the Caused when cold air over the horse latitudes sinks and horse latitudes sinks and produces a high pressure regionproduces a high pressure region

•Blow towards the equator from Blow towards the equator from about 30º north and southabout 30º north and south

Global Wind BeltsGlobal Wind Belts

• PREVAILING WESTERLIES: PREVAILING WESTERLIES: Caused Caused when winds that blow toward the when winds that blow toward the poles are turned toward the east poles are turned toward the east by the Coriolis effect.by the Coriolis effect.

•Between 30º and 60º north and south Between 30º and 60º north and south latitudes.latitudes.

•Blow FROM West to EastBlow FROM West to East•They play an important role in the They play an important role in the

United State’s weatherUnited State’s weather

Global Wind BeltsGlobal Wind Belts

• POLAR EASTERLIES:POLAR EASTERLIES:

•Caused when cold air near the Caused when cold air near the poles sinks and flows back poles sinks and flows back toward lower latitudestoward lower latitudes

•They meet the prevailing They meet the prevailing westerlies at about 60º north and westerlies at about 60º north and south latitudes at the Polar Front.south latitudes at the Polar Front.

•The polar front has a major The polar front has a major effect on weather changes in the effect on weather changes in the US.US.

Chapter 2Chapter 2

•2.4 Water in the Atmosphere2.4 Water in the Atmosphere

Water cycle- movement of water between the Water cycle- movement of water between the atmosphere and earth’s surfaceatmosphere and earth’s surface

2-4 Water in the 2-4 Water in the AtmosphereAtmosphere Evaporation – the process by which Evaporation – the process by which

water molecules in liquid water water molecules in liquid water escape into the air as water vapor.escape into the air as water vapor.

HumidityHumidity

• Humidity – a measure of the Humidity – a measure of the amount of water vapor in the air.amount of water vapor in the air.

• Relative Humidity – the percentage Relative Humidity – the percentage of water vapor in the air compared of water vapor in the air compared to the maximum amount the air to the maximum amount the air could hold.could hold.

– Used on weather reports!Used on weather reports!

Measuring Relative Measuring Relative HumidityHumidity

• Relative humidity can be measured using Relative humidity can be measured using a psychrometer.a psychrometer.

• A psychrometer has two thermometers, a A psychrometer has two thermometers, a wet bulb and a dry bulb.wet bulb and a dry bulb.

• The wet bulb is covered with a damp The wet bulb is covered with a damp fabric.fabric.

• Evaporation cools the wet bulb.Evaporation cools the wet bulb.• Relative humidity can be found by Relative humidity can be found by

comparing the temperature of the wet and comparing the temperature of the wet and dry bulb thermometers.dry bulb thermometers.

A problem…A problem…

• What would the relative humidity be What would the relative humidity be if your dry bulb showed a if your dry bulb showed a temperature of 60ºF and the wet temperature of 60ºF and the wet bulb showed a temperature of 54ºF? bulb showed a temperature of 54ºF? ( a difference of 6º)( a difference of 6º)

AnswerAnswer

• 60 – 54 = 660 – 54 = 6

• Dry bulb temp is 60Dry bulb temp is 60

• Relative Humidity = 68% Relative Humidity = 68%

How Clouds FormHow Clouds Form

• Clouds of all kinds form when water vapor in the air Clouds of all kinds form when water vapor in the air becomes liquid water or ice crystals.becomes liquid water or ice crystals.

• Condensation – the process by which molecules of Condensation – the process by which molecules of water in the air become liquid waterwater in the air become liquid water

• Cold air can hold less water vapor than warm airCold air can hold less water vapor than warm air

• As air cools, the amount of water vapor it can hold As air cools, the amount of water vapor it can hold decreasesdecreases

• Some of the water vapor in the air condenses to Some of the water vapor in the air condenses to form droplets of liquid waterform droplets of liquid water

How Clouds FormHow Clouds Form• Dew Point – the temperature at which condensation Dew Point – the temperature at which condensation

beginsbegins

• For water to condense, tiny particles must be present so For water to condense, tiny particles must be present so the water has a surface on which to condensethe water has a surface on which to condense

• Particles are usually salt crystals, dust from soil, and Particles are usually salt crystals, dust from soil, and smoke. smoke.

• Dew is water than condenses above the freezing point Dew is water than condenses above the freezing point and land on a solid surface such as a blade of grass.and land on a solid surface such as a blade of grass.

• Frost is ice that has been deposited directly onto a Frost is ice that has been deposited directly onto a surface that is below the freezing point.surface that is below the freezing point.

• Clouds form whenever air is cooled to its dew pointClouds form whenever air is cooled to its dew point

Types of CloudsTypes of Clouds• Meteorologists classify clouds into Meteorologists classify clouds into

three main types: three main types:

• cumuluscumulus

• stratus stratus

• cirrus.cirrus.

Types of CloudsTypes of Clouds

• Cumulus clouds look like fluffy, Cumulus clouds look like fluffy, rounded piles of cotton that indicate rounded piles of cotton that indicate nice weather when not tallnice weather when not tall

Cirrocumulus-rows of cotton Cirrocumulus-rows of cotton balls indicating a storm is on balls indicating a storm is on the way.the way.

Cumulonimbus clouds often Cumulonimbus clouds often produce thunderstormsproduce thunderstorms

Stratus clouds form in flat layers that can thicken Stratus clouds form in flat layers that can thicken and can produce drizzle, rain, or snow and can produce drizzle, rain, or snow (nimbostratus)(nimbostratus)

Cirrus clouds are wispy and feathery and Cirrus clouds are wispy and feathery and only form at high altitudes. (made of ice only form at high altitudes. (made of ice

crystalscrystals))

• Altostratus and Altocumulus are Altostratus and Altocumulus are clouds that form 2-6km above clouds that form 2-6km above earth’s surface.earth’s surface.

• Middle level cloudsMiddle level clouds

Clouds that form at or near the ground are called Clouds that form at or near the ground are called fog. Form when the ground cools at night after fog. Form when the ground cools at night after a warm humid day.a warm humid day.

Chapter 2 WeatherChapter 2 Weather

•2.5 Precipitation2.5 Precipitation

PrecipitationPrecipitation

Precipitation is any form of water that Precipitation is any form of water that falls from clouds and reaches Earth’s falls from clouds and reaches Earth’s

surface surface

Types of PrecipitationTypes of Precipitation • Common types of Common types of

precipitation include rain, precipitation include rain, sleet, freezing rain, hail and sleet, freezing rain, hail and snow.snow.

• Rain – most common type of Rain – most common type of precipitation, drops of water precipitation, drops of water are at least 0.5mm in are at least 0.5mm in diameter, smaller drops are diameter, smaller drops are mist and drizzle which usually mist and drizzle which usually fall from nimbostratus cloudsfall from nimbostratus clouds

• Sleet – raindrops freeze as Sleet – raindrops freeze as they fall, ice particles are they fall, ice particles are smaller than 5mm in diametersmaller than 5mm in diameter

• Freezing Rain – raindrops freeze Freezing Rain – raindrops freeze when they touch a cold surfacewhen they touch a cold surface

• Hail – round pellets of ice larger Hail – round pellets of ice larger than 5mm in diameter, only forms than 5mm in diameter, only forms inside cumulonimbus clouds during inside cumulonimbus clouds during thunderstormsthunderstorms

• Snow – water vapor in cloud is Snow – water vapor in cloud is converted directly into ice crystals converted directly into ice crystals called snowflakes, all have six sides called snowflakes, all have six sides or branchesor branches

Measuring PrecipitationMeasuring Precipitation

• Meteorologist measure rainfall with a rain gauge.Meteorologist measure rainfall with a rain gauge.

• Rain gauge – an open-ended can or tube that Rain gauge – an open-ended can or tube that collects rainfall.collects rainfall.

Controlling Precipitation Controlling Precipitation • Droughts – long periods of unusually low Droughts – long periods of unusually low

precipitationprecipitation

• In cloud seeding, tiny crystals of dry ice (solid In cloud seeding, tiny crystals of dry ice (solid carbon dioxide) and silver iodide are sprinkled carbon dioxide) and silver iodide are sprinkled into clouds from airplanes.into clouds from airplanes.

• The super cooled water droplets in the cloud The super cooled water droplets in the cloud can then condense around the silver iodide can then condense around the silver iodide particles. particles.

• Dry Ice cools the water even more so it Dry Ice cools the water even more so it freezes without a surface to condense on.freezes without a surface to condense on.