Earth’s Climate

Earth’s Earth’s Climate Climate

Factors That Determine Climate

Sunlight falling at an angle is spread out over a greater area and therefore causes less heating at steeper angles in polar regions.

The Earth is cold at the poles and warm at the equator

Factors That Determine ClimateTilt of the Earth’s axis

•23.5 towards the sun in summer

•23.5 away from the sun in winter

Polar regions become extremely cold in winter.

Even though the poles get constant sun in summer, the solar angle is so low that the heating is small. Also, polar ice reflects sunlight, further reducing the effect of constant sun.

Solar energy absorption Solar energy reflection

Solstice

Equinox

Equinox

Solstice

Seasonal ChangesMar. 21-June 21

June 21 – Sept. 23

Sept. 23 – Dec. 22

Dec. 22 – Mar. 21

Northern Hemisphere

Spring Summer Fall Winter

Southern Hemisphere

Fall Winter Spring Summer

Northern Hemisphere Southern Hemisphere

March 21 Vernal Equinox12/12 hrs. day and night lengthSun’s direct rays = Equator

Autumnal Equinox12/12 hrs. day and night lengthSun’s direct rays = Equator

June 21 Summer SolsticeLongest day lengthN. Pole = 24hrs of sunlightSun’s direct rays=Tropic of Cancer

Winter SolsticeLongest night lengthS. Pole = 24hrs of darknessSun’s direct rays=Tropic of Cancer

Sept. 23 Autumnal Equinox12/12 hrs. day and night lengthSun’s direct rays = Equator

Vernal Equinox12/12 hrs. day and night lengthSun’s direct rays = Equator

Dec. 21/22 Winter SolsticeLongest night lengthN. Pole = 24hrs of darknessSun’s direct rays=Tropic of Capricorn

Summer SolsticeLongest day lengthN. Pole = 24hrs of sunlightSun’s direct rays=Tropic of Capricorn

Also Watch!!!!http://www.youtube.com/watch?v=WLRA87TKXLM&safety_mode=true&persist_safety_mode=1&safe=active

Weather and ClimateWhat is weather?

Weather is the state of atmospheric conditions that exist over relatively short periods of time, from a few hours to a couple of days).

Weather includes the passing of a thunderstorm, hurricane, or blizzard, and the persistence of a heat wave, or a cold snap.

What is Climate?

Climate is the weather we expect over the period of a month, a season, a decade, or a century.

It is often described in terms of "climate norms" or average weather conditions.

Climographs are graph of monthly average temperature plotted against average precipitation. The temperature points are joined by a line.

Reading a ClimographLocation at the top

Dotted Line Graph = average monthly temp.

Temperature Scale Watch Fº vs. Cº!!

Months at the bottomJFMAMJJASOND

Precipitation Scale, Watch inches or mm!!

Bar Graph = Average Monthly Rainfall…think of a glass filling up w/ water

Analyzing Climographs

Factors That Determine Climate

Latitude:

Warm and moist at the equator, cold and dry at the poles

Altitude/Elevation:

Higher altitudes are colder and dryer

Proximity to landforms: (mtns., deserts, plains, valley)

Mountains can cause clouds an precipitation on the windward side, and dry conditions on the leeward side

Proximity to oceans:

Oceans moderate temperature and increase humidity

Polar or Tropical water currents can influence temperatures

“How do those factors influence a location’s climate?”

Elevation/altitudeFor every 1,000 ft of elevation change, we calculate 3.5°of temperature change

As we rise in elevation, temperature….?

As we drop in elevation, temperature….?

Closeness to Landforms: mtns.

This is how prevailing winds can influence climate

Coastal vs. Inland

• Precipitation:• Receive more rain,

than snow• Humidity acts to

insulate temperatures• Sun goes down, the

moisture retains heat• Temperatures:

• Remain more constant throughout the year

• Cooler Summers, Warmer Winters

• Less variation in yearly averages than inland

• Precipitation:• Typically receive more

snow, than rain• Little humidity, daytime

heat is lost• Sun goes down it gets

cold• Temperatures:

• Have more variation throughout the year

• Cooler winters, Warmer Summers

• Lots of variation in yearly averages

This is how distance from water can influence a location’s climate

City Low (Jan.) High (July) Latitude

1) Los Angeles, CA 64° F 81° F 34.0° N

2) Little Rock, AR 50° F 90° F 34.5° N

3) Seattle, WA 4° F 72° F 47° N

4) Bismarck, ND 18° F 82° F 47° N

5) London, UK 45° F 73° F 51.5° N

6) Warsaw, Poland 32° F 75° F 52.5° N

7) Belfast, Ireland 43° F 64° F 54° N

8) Moscow, Russia 16° F 73° F 56° N

9) Tokyo, Japan 46° F 82° F 35° N

10) Kabul, Afghanistan 36° F 88° F 35° N

11) Beirut, Lebanon 63° F 90° F 34° N

Red= InlandBlue= Coastal

Closeness to Water bodies: ocean currents

How do scientists know what the weather was like in the past?

Climate Data

Direct Measurements:

Observations of air & water temperature, precipitation amount, etc… have been made routinely with accurate instruments for about 150 years

Historical Records:

Clues left in written documents from the past

Paleoclimate:

Properties of the Earth and Atmosphere are determined from clues hidden in the Earth, a kind of forensic science.

Sources of paleoclimate information:

•Ice Cores

•Tree Rings

•Ocean Sediment

Ice Cores

•Ice cores are samples of ice taken from glaciers .

•Air bubbles, dust, and oxygen isotopes get trapped in glacial ice, and can be used to analyze past climate.

•Glaciers become thicker over time, so the deeper you drill the older the ice is.

Glaciers obtain one layer each year, so counting layers is like counting years.

Ice core data can extend back hundreds of thousands of years

•Ice cores can reveal temperature, precipitation, and gas composition of the lower atmosphere

•They also can indicate volcanic eruptions, solar variability, sea-surface productivity and a variety of other climate indicators.

Tree Rings

In temperate regions where there is a distinct growing season, trees generally produce one ring a year

Since tree growth is influenced by climatic conditions, patterns in tree-ring widths, density, and isotopic composition reflect variations in climate. 

Trees can grow to be hundreds to thousands of years old and can contain annually-resolved records of climate for centuries to millennia.

If a tree is fossilized, the age of the tree (how long ago it died) can be determined by examining isotopes.

Isotope ratios are also indicative of temperature change.

Ocean Sediments

Billions of tons of sediment accumulate in the ocean and lake basins each year.

Scientist drill cores of sediment from ocean and lake floors.

Ocean and lake sediments include tiny fossils and chemicals that are used to interpret past climates.

The Greenhouse Effect

The Earth receives ultraviolet (UV) radiation from the sun, absorbs it, and then radiates the energy out as infrared radiation

If the Earth behaved as a simple blackbody then the Earth’s average temperature would be –18 C

However, the Earth’s average temperature is 15 C.

The Earth is warmer because our atmosphere traps some of the outgoing IR radiation. This is a natural process known as the greenhouse effect.

The greenhouse effect is a good thing, without it the Earth would become too cold for life to exist.

However, man’s activities appear to be altering the natural balance.

The Greenhouse Effect