Chapter 6. Climate, Terrestrial Biodiversity, and Aquatic Biodiversity

Section 6-1 Weather and Climate: A Brief

Introduction

What is weather?

Short-term set of physical properties of the troposphere at a particular place and time.

TemperaturePressureHumidityPrecipitationSunshine Cloud cover

What is weather?

• Meteorologists use equipment to obtain data on weather variables:– Atmospheric pressure– Precipitation– Temperatures– Wind speeds locations of air masses and

frontsThis data is fed into computer models to

draw weather maps to forecast the weather

What is Climate?

• Climate is a region’s general pattern of atmospheric of weather conditions over a LONG period of time– Average temperature and average

precipitation are the two main factors that determine a region’s climate

Climate

the average weather patterns for an area overa long period of time (30 - 1,000,000 years).

is

It is determined by

Average Precipitation Average Temperatureand

which are influenced by

latitude altitude ocean currents

and affects

where people live how people livewhat they

grow and eat

Climate

and

its

effects

5 factors that determine global air circulation

patterns1. Uneven heating of Earth2. Seasons3. Earth’s rotation4. Variation of sun’s output5. Properties of air and water

1. Uneven Heating of the Earth

Climate type

Cold

Cool Temperate

Warm Temperate

Tropical

(equator)

Tropical

Warm Temperate

Cool Temperate

Cold

2. Seasons

3. Rotation of Earth

4. Variations in solar output

5. Properties of air and water

• 5. Properties of air and water– Convection Cells –

circulate air, heat, and moisture both vertically and from place to place.

How do ocean currents affect regional climates?• The five factors PLUS differences in water

density create warm and cold ocean currents.

• These currents (driven by winds and earth’s rotation) redistribute heat and therefore influence climate and vegetation– If ocean’s currents suddenly stopped flowing,

there would be deserts in the tropics and thick ice over northern Europe, Siberia, and Canada

– Currents also mix ocean waters and distribute nutrients and dissolved oxygen needed by aquatic organisms

60,000 Nikes spilled into the Pacific

Polar (ice)

Subarctic (snow)

Cool temperate

Warm temperate

Dry

Tropical

Highland

Major upwelling zones

Warm ocean current

Cold ocean current

River

CD ani 2

Warmcurrent Cool

air

Convectioncell

Coolcurrent

Warmair

Equator

Solarradiation

Warmwater

Warmcurrent

Polarfront

Coolcurrent

Coldwater

Ocean Currents

Surface Currents

Midlevel currents

Bottom Currents

Wind

Movement ofsurface water

Diving birds

Nutrients

Upwelling

Fish

Zooplankton

Phytoplankton

Upwellings – winds push surface water away from the land, this water is replaced by cold-nutrient rich bottom water – brings deep cool water to the surface

Cell 3 South

Cold,dry air falls

Moist air rises — rain

Cell 2 South

Cool, dryair falls

Cell 1 South

Moistair rises,cools, andreleasesmoistureas rain

Cell 1 North

Cool, dryair falls

Cell 2 North

Moist air rises — rain

Cell 3 NorthCold,dry airfalls

Polar cap

Arctic tundra

60°

30°

0°

30°

60°

Polar cap

Evergreenconiferous forest

Temperate deciduousforest and grassland

Desert

Tropical deciduous forest

EquatorTropical rain forest

Tropical deciduous forest

DesertTemperate deciduousforest and grassland

Relationship between global air circulation and biomes

El Nino - “The Christ Child”

El Niño is a disruption of the ocean-atmosphere system in the Tropical Pacific having important consequences for weather and climate around the globe.

What is the El Nino-Southern Oscillation (ENSO)?

1) Occurs in the Pacific Ocean2) Prevailing westerly winds weaken

or cease3) Surface water along the South

and North America coasts become warmer

4) The normal upwelling of cold, nutrient rich water are suppressedBad fishing

Normal Conditions

Cold water

Warm water

Thermocline

SOUTHAMERICA

Warm waterspushed westward

AUSTRALIA

EQUATOR

Surface windsblow westward

El Niño Conditions

Cold water

Thermocline

Warm waterWarm water deepens offSouth America

SOUTHAMERICA

Warm waterflow stoppedor reversed

AUSTRALIA

EQUATOR

Drought inAustralia andSoutheast Asia

Winds weaken,causing updraftsand storms

El Niño

Unusually warm periods

Unusually high rainfall

Drought

La Nina

• Cooling counterpart of El Nino• Means more Atlantic hurricanes,

colder winters in Canada and northeastern US, warmer and drier winters in the southeastern and southwestern US and more wildfires in Florida

How does the chemical make-up of the atmosphere lead to the greenhouse effect?

The Greenhouse Effect

1) Water vapor H2O

2) Carbon dioxide CO2

3) Methane CH4

4) Nitrous oxide N2O5) Chlorofluorocarbons

CFCs

Major Greenhouse Gases

Are Greenhouse Gases GOOD or BAD?

• THEY’RE BOTH• GOOD - without greenhouse gases,

the Earth would be too cold for life• BAD - too many greenhouse gases

may lead to global warming

Where do greenhouse gases come from?

• ALL OF US!!!• Burning fossil fuels releases:

– CO2

– H2O

– N2O

• Cows release methane (CH4)• Various refrigerants use CFCs

How does the chemical make-up of the

atmosphere create the ozone layer?

Is this what the hole in the ozone layer looks like?

Did Mrs. Gallo destroy the OZONE… it’s possible…

Ozone• In a nutshell – we will discuss in detail later in the

year– In stratosphere oxygen (O2) is converted to

ozone (O3) and back to oxygen by a sequence of reactions initiated by UV radiation from the sun

– Results in a thin veil protecting us from 95% of sun’s harmful UV radiation

– Evidence indicates that chemicals added to atmosphere by our activities are decreasing the level of protection

– Thermal cap – warm layer of air created by ozone layer that prevent churning gases in the troposphere from entering the stratosphere, important in determining average temp of troposphere and climate

a Winds carrymoisture inland

from Pacific Ocean

b Clouds, rain onwindward side ofmountain range

c Rain shadow onleeward side ofmountain range

Moist habitats

Dry habitats

Rain Shadow Effect - lower precipitation and semiarid or arid conditions on the leeward side of a mountain-

Microclimates – local climatic conditions that differ from the general climate of a region

Rain Shadow Effect

Cool airdescends

Land warmer thansea; breeze flowsonshore

Warm air ascends

Sea Breeze

Warm air ascends

Land cooler thansea; breeze flowsoffshore

Cool airdescends

Land Breeze

Weather Extremes

• Tornadoes

• Tropical cyclonesAtlantic Ocean = hurricanesPacific Ocean = typhoons

Descendingcool air

Severethunderstorm

Tornado forms whencool downdraft andwarm updraft of airmeet and interact

Risingwarm air

Severe thunderstormscan trigger a numberof smaller tornadoes

Risingupdraftof air

Rising winds exitfrom the storm athigh altitudes.

The calm centraleye usually is about

24 kilometers(15 miles) wide.

Moist surface windsspiral in towards thecenter of the storm

Gales circle the eye at speedsof up to 320 kilometers

(200 miles) per hour.

Tropical Cyclones

Hurricane Sandy - FRANKENSTORM

• Hurricane Sandy was the largest Atlantic hurricane on record

• The second-costliest Atlantic hurricane in history, only surpassed by Hurricane Katrina in 2005

• Hurricane - A hurricane is a tropical storm with winds that have reached a constant speed of 74 miles per hour or more. The eye of a storm is usually 20-30 miles wide and may extend over 400 miles. The dangers of a storm include torrential rains, high winds and storm surges. A hurricane can last for 2 weeks or more over open water and can run a path across the entire length of the Eastern Seaboard

• Video – Weather Channel

Risk of Tornadoes

Highest

High

Medium

Low

Tropical CycloneFrequency

High

Moderately high

Gulf of Alaska

Prince WilliamSound

CANADA

UNITED STATES

Grand Banks

Atlantic OceanMEXICO