Earth’s Atmosphere

Energy from the SUN – INcoming SOLAr radiaTION

Through the seasons, it heats our world, some parts more and some less and this drives both climate (global) and weather (local).

The electromagnetic spectrum includes visible light, as well as X-rays, ultraviolet rays and infrared rays.

Climate is the average temperature and moisture conditions over a long period of time.

Water Budget – a system of accounting for moisture income, storage, and outgo for the soil in a specific area.

Humid climates are those in which the total amount of precipitation is greater than the total amount of Potential Evapotranspiration (Loss of water to atmosphere)

Arid climates have significantly more total Potential Evapotranspiration than Precipitation

Latitude• Most important

factor in determining climate, especially temperatures

• As latitude increases, yearly temperature range (difference between highest and lowest temperature) increases.

•

As elevation increases, average yearly temperature decreases.

MarineMarine ContinentalLocation: Ocean/large lakeOcean/large lake Interior (land)Interior (land)Winds from: OCEANOCEAN LANDLANDSummers: Cooler than Cooler than

Average (Mild)Average (Mild)Warmer than Warmer than average (HOT)average (HOT)

Winters: Warmer than Warmer than Ave. (Mild)Ave. (Mild)

Colder than Colder than Ave.Ave.(Harsh)(Harsh)

Example: San Francisco, San Francisco, LA, DCLA, DC

Kansas, NE, IA, Kansas, NE, IA, SyracuseSyracuse

Uneven heating of the Earth produces global wind belts and pressure belts. These “pressure belts” determine the wetness or dryness of a particular location. Low pressure Low pressure occurs where air is rising and thus precipitation occurs. High High pressure regions pressure regions are areas that are areas that lack rainfalllack rainfall (DRY).

The "Global Conveyer Belt" shows how the oceans move energy from the tropics to the poles and back again in order to moderate Earth's climate. This is accomplished through long-term ocean circulation.

•Interesting Interesting fact:fact: It takes up It takes up to 1000 years to 1000 years for water to for water to completely completely circulate the circulate the oceans!oceans!

A warm ocean current resulting from a reversal of the ocean current in the Pacific which results in climate variability around the globe.

Orographic Effect – Mountains act as barriers to prevailing winds. As the wind hits the windward side of a mountain, the air is forced up, cools, condenses and forms clouds with precipitation.

Windward side – Side of the mountain that is exposed to the wind. WET

Leeward Side – Descending air warms and it holds more moisture, making it DRY.

WINDWARD

LEEWARD

Prevailing Wind

Air Rise

s, Exp

ands

&

Cools

Air Sinks, Compresses & Warms

*Why does rising air cool? *As air temperature decreases, its ability to hold water___DECREASESDECREASES______*Why does falling air warm?

Topography

Cascade Mountains

Condensation & Precipitation

Weather = the condition of the atmospheric variables, such as temperature, air pressure, wind, and water vapor, at a particular location for a relatively short period of time.

Direct result of TILT & parallelism in orbit distribute energy from vertical to oblique rays

Tilt (inclination) spreads concentration of energy over broader area

This UNEVEN HEATING causes earth’s atmosphere to react and become a gigantic engine that produces an infinite variety of WEATHER.

1. Temperature2. Air Pressure3. Moisture Conditions (Precipitation & Humidity)4. Wind (Speed & Direction)

Barometer – measures AIR PRESSURE

Pyschrometer – measures amount of water vapor (relative humidity)

Rain Gauge – Measures liquid precipitation

Wind Vane – measures wind direction

Anemometer – measures wind speed

Thermometer – measures air temperature

Note: In the USA we still use degrees Fahrenheit – the rest of the world measures in oCelsius

Atmosphere

Complete the questions in the note packet while you watch!

Composition of the lower atmosphere (troposphere):

1. Nitrogen = 78% used by bacteria in soil to make nitrates

2. Oxygen = 21% used by humans and animals for respiration

3. Argon = 0.84% 4. Carbon Dioxide = 0.03% used by

green plants to make food

5. Others = 0.01% which include:

Helium, Hydrogen, Ozone, Krypton, neon and xenon

6. Also: water vapor, dust particles and pollution

What is Ozone? O3 – we breathe O2 It occurs naturally in trace amounts in the

stratosphere. Ozone protects life on Earth from the

Sun’s UV radiation. Ozone is created naturally when sunlight

splits apart O2 into single O atoms – these then bond to form more O2 or O3

NO!! The ozone molecules are randomly

scattered among other particles in the stratosphere layer

Ozone molecules are exceedingly rare: In every one million molecules of air, fewer than 10 are ozone

Filters out harmful UV radiation, which can cause skin cancer, cataracts, faster aging & weakened immune systems

UV is also harmful to plants & marine life and it can disrupt the food chain

CFC – chlorofluorocarbons, which are used in:

1. Coolants in refrigerators2. Propellants in aerosol cans3. Electronic cleaning solvents

Ground-level ozone triggers chest pain, nausea, bronchitis, reduced lung capacity, and aggravates asthma

Air Quality Index An index for reporting daily air quality Focuses on health effects that can happen within a

few days of breathing polluted air Used for: ground level ozone, particulate matter,

carbon dioxide, sulfur dioxide, and nitrogen dioxide

AIR POLLUTION-any substance in the atmosphere that is harmful ( usually produce long term health effects and can cause death )

Main Sources – burning fossil fuels ( coal and petroleum )

Ex: SOx, CO ( carbon monoxide ), lead, various hydrocarbons

Acid Rain ( precipitation ) – side effect of air pollution- gases from burning fossil fuels combine with water in the air to

produce acids, then falls back to the earth as precipitation Long Term effects: kills fish, soil contamination, destruction of plants, trees, and crops

Temperature Inversion ( very serious problem )

Mt. Mitchell, NC

In order for this reaction to occur, it must be extremely cold. Conditions for this reaction are perfect over Antarctica in the winter months.

Can we fix it?? The ozone hole will fix itself given enough

time Many major countries, including the U.S.,

have placed heavy restrictions on ozone-polluting substances

December 2013

The false-color view of the monthly-averaged total ozone over the Antarctic pole. The blue and purple colors are where there is the least ozone, and the yellows and reds are where there is more ozone.

1. 6% reflected from atmospheric scattering (aerosols)

2. 20% reflected by clouds3. 4% Reradiation:

Reflected by Earth’s surface

4. 3% Absorbed by clouds5. 51% Absorbed by

Earth’s surface6. 16% Absorbed by

atmosphere

Short wave energy (UV) from the Sun comes in and heats the Earth

As heat reradiates up from the earth, it is emitted in the form of LONG wave energy (infrared)

The long wave energy becomes trapped by gases in the troposphere

This trapped gas warms the air much like your car on a hot day.

Water vapor Methane (CH4) Carbon dioxide Nitrous oxide CFCs (chlorofluorocarbons)

CONDUCTION– Transfer of heat within solidsatoms are closely packed.

CONVECTION – Transfer of heat in liquid or

gas results from differences in

density

RADIATION: The emission or giving off of

energy HEAT

Heat in the atmosphere is recorded as a temperature reading and can then be plotted on a map to see a picture of change.

• ISOTHERMS are lines that connect points of equal temperature. Showing temperature distribution in this way making patterns

easier to see.

Why do the isotherms seem to run E – W across the map?

LAND vs. WATERLand heats up and cools faster than water

ColorDARK vs. LIGHT

Darker colors tend to absorb more insolation than they reflect.

Surfaces with lighter colors tend to reflect more insolation than they absorb.

TEXTURESmooth vs. Rough

A surface which has a rough or uneven surface will absorb more insolation.

Phase Change Diagram

The primary source of moisture for the atmosphere are the OCEANS.

Other sources include: Lakes, Rivers, streams Transpiration

Moisture in the atmosphere exists in all three states/phases.

1)Gas – known as water vapor2)Liquid – tiny droplets suspended in the air

that form clouds3)Solid – tiny crystals suspended in the air

that form clouds

HUMIDITY is the general term used to describe the amount of water vapor in the air

Temperature determines the amount of water vapor the air can hold.

As air temperature INCREASES, the amount of water vapor the air can hold INCREASES.

e) Saturation –100% humidity in the atmosphere (precipitation results)

At 350C, a cubic meter of air can hold 35 g/m3 of water vapor.

Temperature – As temperature increases, evaporation increasesWind – As wind increases, evaporation increasesSurface Area – As surface area increases, evaporation increasesHumidity – As humidity goes UP, evaporation rates go DOWN

The temperature to which air must be cooled to reach saturation. And Condense…….and make clouds!

If the air temp drops down to the dew point, condensation will occur. The dew point can tell us how high clouds will form. Clouds form where condensation is occurring.

a) The drier the air, the faster/more evaporation will occur resulting in greater/more cooling. In turn, the difference in temperature between the dry bulb and wet bulb will be greater/more.

b. The more humid the air, the LESS evaporation will occur resulting in LESS cooling of the wet bulb thermometer. In turn, the difference in temperature between the dry bulb and wet bulb will be LESS

c. At saturation (100% humidity), the temperature difference between the dry bulb and wet bulb would be zero and precipitation will usually occur!.

Maximum amount of water vapor the air can hold at a given temperature.

The actual amount of water vapor in the air is the absolute humidity.

Relative humidity tells "how full" the air is with water. It is expressed in %. 100% is full and can't hold any more. It is saturated.

Warm Air = higher humidity (wet) Cold Air = low humidity (dry)

Changing Air Temperature

If temperature increases and moisture in the air remains the same, relative humidity will decrease.

Changing Absolute HumidityTemperature

Relative Humidity

If moisture content of the air increases and temperature stays the same, relative humidity will increase.

Complete the worksheet while watching!

It’s easy; if…..It’s easy; if…..– You have ½ a brainYou have ½ a brain– Pay attentionPay attention– Do your practice!Do your practice!

Using the chart to determine Using the chart to determine Dew Point & Relative HumidityDew Point & Relative Humidity

The “Dry Bulb”The “Dry Bulb” Don’t let it fool you. Don’t let it fool you.

It is just a It is just a thermometer.thermometer.

It measures the air It measures the air temperature.temperature.

Duh!Duh!

20°C

The “Wet Bulb”The “Wet Bulb” Has a little wet Has a little wet

booty tied to the booty tied to the bottom.bottom.

Gets cool when Gets cool when water evaporates.water evaporates. 12°C

Wet Booty

A Dry Day…A Dry Day… A lot of moisture A lot of moisture

will evaporate.will evaporate. The wet bulb will The wet bulb will

be a lot cooler be a lot cooler than the dry bulb.than the dry bulb. 8°C

20°C

Difference between wet bulb & dry bulb is 12 °C.

20°C14°C12°C

A Humid Day…A Humid Day… A little bit of A little bit of

moisture will moisture will evaporate.evaporate.

The wet bulb will The wet bulb will not be much not be much cooler than the cooler than the dry bulb.dry bulb.

14°C

20°C

Difference between wet bulb & dry bulb is 6 °C.

Page of your notes has a Page of your notes has a chart with Dewpoint (DPT) chart with Dewpoint (DPT)

and Relative Humidity (RH)!and Relative Humidity (RH)! Warning #1: Be sure to READ the correct Warning #1: Be sure to READ the correct

chart: DPT or RHchart: DPT or RH Warning #2: Dew Point Temperature IS NOT Warning #2: Dew Point Temperature IS NOT

“Difference between wet bulb and dry bulb”.“Difference between wet bulb and dry bulb”. Warning #3: The wet bulb temp IS NOT the Warning #3: The wet bulb temp IS NOT the

DPT.DPT.

Dry-bulb temperature is your air temperature.

20 °C

14 °C

4 °C

Subtract (the difference) between the dry bulb and wet bulb

14°C20°C

20-14=6

16°C18°C

18-16=2

8°C20°C

20-8=12

Put it all together

Relative Humidity = 11%

10°C14°C

14-10=4

Relative Humidity = 60%

10°C14°C

14-10=4

Dew Point = 6°C

The Dew Point Chart works the same way

Try These.Try These.Dry Bulb Wet Bulb R Humidity DPT

26°C 20 °C

6 °C 5 °C

12 °C 8 °C

57% 17 °C°C86% 4 °C°C57% 4 °C°C

Now do the worksheet for homework on the next page of your notes

How Do Clouds Form?

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Adiabatic Cooling - As air rises, the atmospheric pressure surrounding the parcel of air decreases. Therefore, the parcel of air expands as it rises.

As it expands, it becomes cooler. When the temperature of this parcel of air falls to its dew point temperature, the water vapor in the air condenses and a cloud appears in the sky.

Air pressure acts equally in all directions; it also exists within any object containing air like a building, the human body and “empty” bottles.

When you mess with the pressure – “bad” things happen!~CRUSH!

a. Factors/Variables that cause atmospheric pressure to change:

TemperatureMoistureAltitude

b. Effect of temperature on air pressure:As air temperature increases; (air molecules move further apart/become less dense) – the air pressure decreases

c. Effect of moisture on air pressure:

As humidity increases, air pressure decreases – because when water vapor molecules enter the air, they replace heavier air molecules

d. Effect of altitude on air pressure As altitude

increases, air pressure decreases (less air is above and air is less dense

a. Isobars are lines that connect points of equal air pressure. Showing air pressure distribution in this way makes patterns easier to see.On U.S. Weather Bureau maps, the interval between isobars is 4 mb.

On weather maps, barometric pressure is represented by a three-digit number to the upper right of a circle; this circle represents a city on the map.

053

Rules to follow to determine the value of this number:

A decimal point is omitted between the last 2 digits on the right.

The number 9 or 10 is omitted in front of this number. If the original number is above 500, place a 9 in front. If it is below500, place a 10 in front. (Hint: use whichever will give a result closest to 1000 mb)

Example: 053 – 1005.3

Components of Weather

High Pressure System: Anticyclone

Winds blow in a clockwise direction and away from the center

Caused by: More dense air “falling”

Components of Weather

Low Pressure System: Depression or Cyclone

Winds move Counterclockwise and IN towards the center

Therefore – once they get to the middle, there is nowhere to go but UP

The horizontal movement of air parallel to Earth’s surface.

All wind deflects to the RIGHT in the Northern Hemisphere!

How is Wind Formed?

Sun heats ground

Ground heats air

Air rises and cools in

the atmosphere

As air cools it can no

longer rise

Cold air sinks

WIND moves from high to low pressure

LOWHIGH

1. Uneven heating at Earth’s surface2. Examples:

a. Land vs. waterb. Poles vs. equatorc. Dark forest vs. snow field

1. Winds always blow from regions of high pressure to regions of low pressure.

Winds are named for the direction that they come FROM

The direction of the line always points to the center of the circle (in this case pointing east) and indicates the direction in which the wind is blowing at this location.

Each “feather” represents the wind speed – Whole feather = 10 knots Half feather = 5 knots

feather

North Westerly Wind

2. The speed of the wind is determined by the difference in air pressure.

3. Pressure gradient – difference in air pressure ÷ distance between cities.

4. As the pressure gradient increases (isobars are very close together), wind speed increases.

a. The coriolis effect – Earth’s rotation on it’s axis causes winds to be deflected to the right in the northern hemisphere and to the left in the southern hemisphere.

The unequal distribution of Insolation causes unequal heating of the Earth which causes differences in pressure which result in winds.

Cooler air, being more dense, sinks toward Earth due to gravity, causing warmer, less dense air to rise

Earth’s rotation causes the Coriolis Effect which results in the three (or six) cell circulation of winds as illustrated in your notes.

Components of Weather

Air Masses

What is an Air Mass?

An air mass is a large body of air in the troposphere moving in a particular direction, with the same temperature, pressure and humidity throughout.

Components of WeatherAir Masses Affecting the U.S.

2. Types of Air Massesa) Tropical – originates in the tropics (low

latitudes). Characterized by warm air.b) Polar – originates in polar regions

(high latitudes). It is characterized by cold air.

c) Arctic – originates in ice covered arctic regions (winter only). It is very cold and dry.

d. Continental – think LAND. It is dry.

e. Maritime – think SEA. It is wet.

3. Air masses are a combination of temperature and moisture conditions.

It’s right here in It’s right here in ESRTESRT

Types of Frontsa. Cold

b. Warmc. Stationaryd. Occluded

IT’S in the ESRT!

IT’S in the ESRT!

The Stages of Front Formation

Warm Front Cold Front Occluded FrontWarm airWarm air Cold Air –moves fastCold Air –moves fast Cold air meets warm Cold air meets warm

air and mixesair and mixesShowers for long Showers for long periodperiod

Air is dense and hugs the Air is dense and hugs the groundground

precipitationprecipitation

Lots of Clouds as air Lots of Clouds as air rises uprises up

““bullies” the warm air UP bullies” the warm air UP quicklyquickly

Wind changesWind changes

Covers wide areaCovers wide area Brings intense change – Brings intense change – brief periods of stormy brief periods of stormy weather (severe)weather (severe)

Thunderstorms, lightning, Thunderstorms, lightning, tornadoestornadoes

Stationary Front: Warm and Cold air meet head on and neither gives way. Low pressure usually “track” along a stationary front bringing heavy, steady precipitation

Table is on page 26 of notes!

Thunderstorms: A storm that generates lightning and thunder. Frequently produce strong winds, heavy rain, and

hail. At any given time, there are an estimated 2000

thunderstorms in progress on Earth. In the US, Florida and the eastern Gulf Coast

region experience the most activity. Develop when warm, humid air rises in an

unstable environment.

Lightning

Tornadoes Violent windstorms that take the form of a

rotating column of air called a vortex, which extends downward from a cumulonimbus cloud.

The US experiences approximately 700 tornadoes each year.

Greatest occurrence is from April-June (but can happen anytime).

Most frequently in the Central USA! Unique….. Measured using the Enhanced Fujita Scale.

The Birth of a Tornado

A hurricane is a heat engine that gets its energy from warm ocean water. These storms develop from tropical depressions which form off the coast of Africa in the warm Atlantic waters. When water vapor evaporates it absorbs energy in the form of heat. As the vapor rises it cools within the tropical depression, it condenses, releasing heat which sustains the system.

•A tropical depression becomes a hurricane when its sustained recorded winds reach 74 mph.

•Although hurricane forecasting has improved over the years tremendously, the path of these storms may only

be approximated.

What do you mean there are no more Earth

Science notes??