The climate in any one part of the world is influenced by a number of factors. It is the interaction of these parameters which determines the ultimate precipitation and thermal patterns, which in turn strongly influences the biota of the region. For example, the rain forest is a product of its non-varying warm temperature ( 80 - 90' F s year round) and it high rainfall ( 150-200 in / yr.)

As our climate changes with global warming, its impact on all species is evident:

• Meta-analyses on 143 previously published studies reveal a consistent temperature-related shift, or 'fingerprint' in a number of species from around the globe. More than 80% of the 1,400 plant and animal species studied show changes in the direction expected on the basis of known physiological constraints of species. Of those species showing a change in spring phenology (earlier arrival, for example), the average rate of change has been approximately 5 days earlier per decade with an average study length of three decades. One of the biggest changes was in the breeding of the Common Murre which has advanced by 24 days per decade. [Source: Nature 421: 57-60].

"The thing of concern is the decoupling of communities that we know of today," said Terry L. Root, an ecologist and senior fellow at Stanford University's Institute for International Studies and one of the Wildlife Society study's authors. "Species shift differentially. It could cause a lot of trouble."

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The primary factors which lead to the climate of a given area include:

1. Location on the earth's surface:

Observation 1. The earth is round, thus regions at the equator closest to the sun obtain more direct sunlight all year round. At the poles, light hits at an angle, and energy is lost due to reflection out to space and the greater spread of energy. Thus equatorial regions have highest solar input and to an extent higher productivity (given it also has higher precipitation).

Observation 2. The earth tilts. From the diagram you can see why the seasons occur. Work this out for yourself with a globe and flashlight

. However the earth's tilt is not constant. Every thousands of years the earth straightens out a bit , thus the poles get less sunlight and an ice age occurs.

Observation 3.
Every 11 years the sun undergoes a period of activity called the "solar maximum", followed by a period of quiet called the "solar minimum". During the solar maximum there are many sunspots, solar flares, and coronal mass ejections, all of which can affect communications and weather here on Earth.
One way climatologists track solar activity is by observing sunspots. Sunspots are relatively cool areas that appear as dark blemishes on the face of the sun. They are formed when magnetic field lines just below the sun's surface are twisted and poke though the solar photosphere. The twisted magnetic field above sunspots are sites where solar flares are observed to occur, and we are now beginning to understand the connection between solar flares and sunspots.

The apparent linkage between sunspot cycles and recent climatic variability. Over the last 300 years there appears to be a correlation between climate variability and sunspot cycles. No linking mechanism has been discovered, and this seeming correlation may be purely coincidental—or maybe it is not.

Observation 5. Since the equatorial regions have more solar input their air masses heat up more readily. Warmer air is lighter air... so it rises. Eventually as it approaches the higher atmosphere it cools down.

Now, cold air holds less water than warm air. At this point it drops its moisture- right over the Tropical rainforest areas. As the air cools down further, it gets heavier and drops till it hits the ground. But now, it can warm up again as it absorbs the heat radiating from the earth.

However warm air holds more moisture, so it not only picks up heat energy but also moisture from the ground it its approaching. This acts to dry out the land below the descending air mass creating deserts.

Eventually as it moves over the land it gains more heat energy till it becomes light enough to rise once more. If you have a globe try to find the major desert areas... are they in the latitudes you would expect?

The polar and tropical jet streams. The polar jet stream is stronger than the tropical jet stream. Although these are typical distributions of the jet streams, the polar jet frequently displaces the tropical jet equatorward.

Winds in the US:

The source areas of major air masses that influence climate and weather patterns over North America. cP, continental polar; mP, maritime polar; mT, maritime tropical; cT, continental tropical.

The air masses as they move up and down are deflected. Why? The earth is not moving at the same speed as these air masses. Also, the wind must move less at the poles than at the equator. How would these 2 factors help explain the deflection? For a great explanation of the Coriolis Effect see this site:http://www.windpower.dk/tour/wres/coriolis.htm

2.Gases in the atmosphere:

During the day light radiates towards the earth and moves back out into space. At night however radiation only occurs outward. Molecules in the atmosphere act to interfere with wavelengths radiating out into space. They deflect some of them, causing them to reradiate back to earth. This helps cause the air to stay warm. The more the molecules which can absorb the appropriate wavelengths, the more energy is reradiated to earth and Global warming occurs. Look at the diagram which illustrates this.

Four gases are especially potent with respect to their ability to reradiate. See the diagram which allows you to view the increase of these greenhouse gases.

3. Oceanic currents closest to the area:

First view the prevailing oceanic currents on the map.

Currents in the N. hemisphere moving northwards from the tropics bring warm waters which heat the surrounding air and land surfaces. Britain is much warmer than it should be due to the Gulf current. If however the current moves from a colder area to a more southerly location in the N. hemisphere as along the N. America west coast, then it will cool down that area ( example. San Franciso is colder year round than it should be due to the Pacific Current.

The ocean conveyor belt circulation pattern. Dense, cold, salty water sinking off the coast of Greenland sets in motion this immense flow of water through the oceans. After looping through the southern oceans and into the Pacific, the water is warmed, less salty, and rises to the surface of the ocean. The return flow on the surface across the Atlantic is the Gulf Stream that transports vast amounts of heat energy northward. (Broecker, 1989.)

The El Niño Southern Oscillation (ENSO) forms as a result of reduced air pressure over the central Pacific Ocean. This leads to a reduction in wind speed and less warm surface water being piled up in the western Pacific. The ocean slops back eastward causing sea temperatures along the Pacific rim of North and South America to rise. This simple change in air pressure sets in motion a chain of events that affect global climate every three to seven years as they induce an El Niño event.

A critical current is the one moving northerly from the Antarctic along the western coast of S. America.

The current normally brings heavy cold waters which eventually sink causing an upwelling. This upwelling is critical as it brings nutrients from the ocean floor upward to fertilize phytoplankton and moves oxygen down. This flow increases the marine ecosystem's productivity so that fish abound in this region. The current then continues westerly to Australia & Indonesia resulting in cold air masses meeting warm air masses. This results in the annual monsoons which saturate these areas allowing desperately needed annual inputs of moisture

However every 3- 7 years, El Nino occurs. It is thought that perhaps a warming of waters in the Pacific tropical waters (due to increasing number of phytoplankton ; their pigments absorb more light heating up the water) prevents the current from moving as far northerly as usual. Thus the upwelling does not occur, the cold current is shifted more easterly which causes the air masses above to move north and east finally reaching Texas & California. These areas now get the downpour that the Pacific regions should have and results in the flooding of these areas as we have had in recent years.

Worldwide changes in precipitation and temperature induced by a “typical” El Niño event. Each El Niño event produces a somewhat different climate pattern, but on average they would conform to those shown here.

The historical record of ENSO events 1950–2001. A pattern of increasing El Niño intensity is evident since 1975. Data are expressed as a standardized departure from the mean value for the Multivariate ENSO Index for the period 1950–1993. (Data from NOAA-CIRES climate diagnostics center, University of Colorado at Boulder.)

4. Montane effect:

a. First recall that cold air is dry and warm air holds more moisture. Thus the Tundra is exceedingly cold and dry, and the winds from Canada that hit us in the winter may cause our skin to dry out. The warm winds from the south always hold more moisture. When they hit a cold spot and their temperature drops, they can no longer hold their moisture and down pours the rain. So in Maryland, when in winter, warmer winds from the Gulf hit the cold winds from the North, we reap a ton of snow.

Now we will apply this to the mountain effect. As an air mass approaches a mountain as on our West coast it is warm and holds much moisture.

As it is pushed up the mountain, it cools down, and no longer can hold that moisture- thus rain falls down the western slopes of the Sierras. As the winds now descend the mountain, they get warmer as they absorb the heat of the land. They now can hold more water but they were previously wrung out. Where to get the moisture? As they hit the shadow side of the mountain, they pull the moisture out of the ground, creating a desert. So out west, the deserts ( cold up N and hot down South) are a result of this montane effect. If you were to look over the globe, you would see the same phenomenon occurring.