It all starts with the SUN!

The  Sun’s energy  is  efficiently  stored  on  Earth  in  such  things  as oil,  coal,  and  wood (plant materials) .  

Each  of  these  was  produced  by some biological means when the sun acted upon living organisms.

Our existence depends on the Sun because without the Sun, there would be virtually no warmth on Earth, no food for plant life, and no plants to feed animal life, as the sun drives the hydrologic cycle.

Although the Sun radiates its energy in all directions, only a small portion reaches our atmosphere.

This relatively small portion of the Sun’s total energy represents a large portion of the heat energy for our Earth. This thermal energy is of vast importance to our meteorology.

Convection is the movement of molecules within fluids (liquids and gases). It cannot take place in solids, since diffusion cannot move among molecules of a fixed nature.

Convection is one of the major modes of heat transfer on Earth. Convective heat takes place through diffusion – the random Brownian motion of individual particles in the fluid.

It is through radiation that the sun’s energy reaches us here on Earth, and convection that it moves through our atmosphere and hydrosphere (both of which are fluid in nature) The solid Earth conducts thermal energy.[1]

Thermal energy transfer on Earth occurs in several different ways.

How is energy transferred through Earth’s solid surface?

What is the major mode of thermal energy transfer on Earth?

Why is Earth so efficient at convection?

What is the ultimate source of most of the energy on Earth?

Give an example of radiant energy transfer on Earth.

Atmospheric or air pressure is the force exerted on the Earth’s surface by the weight of the air above the surface.

• created by the molecules’ Sizes Motion Density (number present)

Air pressure is not uniform across the Earth, however.

These pressure differences are the result of low and high air pressure systems which are caused by unequal heating across the Earth's surface.

Atmospheric circulation patterns are one of the factors responsible for the distribution of thermal energy on the surface of the Earth. Once the sun’s energy reaches us, it doesn’t just stay in one place.

The distribution of thermal energy, of course, is what drives weather at the surface of our planet.

For the most part, air moves along pressure gradients from conditions of high pressure to lower pressure; warm air rises, cold air sinks.

If the high pressure area is very close to the low pressure area, or if the pressure difference is very great, the wind can blow very fast.

Things to notice:

• Winds are named for the direction from which they COME

• Certain latitudes are important in global circulation patterns

Observe how all wind directions are deflected in the northern and southern hemisphere, due to the Coriolis Force.

Movements of air are influenced by several factors, including the motion of the Earth itself, as well as gravity.What other forces? Notice that the equator spins with a greater velocity than the pole.

The differential velocities associated with the Earth’s rotation give rise to an effect on the air known as the Coriolis Force

Describe why there is wind on Earth.

What causes pressure difference in the atmosphere of Earth?

The higher in altitude you go on Earth, the _____ the air pressure.

What is the origin of Coriolis force?

What direction does Coriolis force deflect air in the northern and southern hemispheres?

• At the equator warm air rises and diverges aloft toward each hemisphere's poles

• Around 30° N & S latitudes, the air has cooled sufficiently to begin sinking. This colder sinking air forms a high at the surface (the Subtropical High). • This is known as the Hadley Cell and as it reaches the surface, it spreads out such that the flow returns to the equatorial zone to complete the cell movement.

Jeopardy Reflection :I will give you the answer, and you will write the question. Phrase it as they do on Jeopardy! (Such as “What is…or Who is…”)

This force is a result of differential rotational

velocities experienced at the poles, and the equator of

Earth.

• Between 30 and 60° latitudes the Ferrel Cell experiences a reversed flow pattern of the Hadley Cell. • Warm (but not hot, as in the equatorial zone), moist air around 60° latitude rises and draws in the cooler 30° latitude air to replace it. This causes an area of very low wind conditions, known as the horse latitudes.•The warm air reaching altitude moves towards the equator, cooling as it goes, and then sinks where it encounters air from the Hadley Cell.

• Surface air in the Ferrel Cell flows poleward and again is deflected to the right (north) and left (south).

The smallest global circulation cell is the Polar Cell. With the circulation patterns established in both the Hadley and Ferrel Cells, you could probably deduce the air flow within the Polar Cell without a diagram.

As you can see, they indeed flow equatorially at the surface, and poleward aloft.

Hadley Cell

Ferrel Cell

Starting at the equator, the term ITCZ refers to the InterTropical Convergence Zone, which indicates that surface air (windflow) is converging from both hemispheres. The direction of

prevailing winds between the Subtropical Lows and the ITCZ is westward in both hemispheres, and are called “Easterlies”, or Tradewinds.

Generally, prevailing surface winds between the Subtropical high, and the Subpolar low flow in an eastward direction, making them “Westerlies”. Remember, winds are named for the direction they flow FROM.

Given this, can you deduce the direction of the polar winds?

Describe how and where a Hadley Cell forms.

Describe how and where a Ferrel Cell forms.

What is the smallest global circulation pattern?

What is the ITCZ, and where does it form?

What is another name given to the Easterly winds at the equator?

Any discussion of global circulation patterns cannot be complete without talking about the Jet Streams you hear about on the Weather News.

•These function as steering currents for surface air masses and as zonal boundaries for sharp differences in temperature.

•Jets are something like "rivers of air" found at high altitudes and noted for their high speeds.

•They develop just below the Tropopause.

In the Northern Hemisphere, there are two such streams: the Mid-Latitude Jet - which is the one usually affecting weather in the U.S., Europe and Asia, and the Subtropical Jet. Typical positions of the two are shown in this diagram

What is the tropopause?The tropopause is the boundary of atmosphere that forms between the troposphere and stratosphere.

Not to be outdone…the southern hemisphere also has its version of polar and subtropical jets, as seen in the image above.

The Jet Streams affecting the U.S. move up and down across the continent, being directly over the area where temperature differential between surface and aloft is greatest.

When it is farther north, the weather to its south tends to be mild or at least less cold.

When the stream swings south, very cold, often harsh weather prevails at the surface on the northern side.

This diagram shows two typical positions

at the height of Summer and of

Winter. With wind speeds between 50 and 250 mph, it is easy to see how the economics of air travel may be influenced.

What is the difference between typical westerlies, like we already learned about, and the jet stream?

In which direction do jet streams flow in the hemispheres?

During which season in North America, does the midlatitude jet usually migrate southward?

What are jet streams in the southern hemisphere called?

Why are jet streams economically important?

What do jet streams do, besides slow down westward moving aircraft?

Atlantic hurricanes usually begin off the African coast in subtropical waters that are very warm in summer - often in excess of 28° C. Ocean water is vaporized by the Sun's rays, producing warm air that rises. Its moisture then condenses with upward cooling, releasing great amounts of heat that drive the disturbance until, if conditions persist, it graduates into a hurricane. Hurricanes in the

Atlantic tend to average from about 5 to 15 events per year. Worldwide, between 80 and 100 normally occur. Most are Categories 1 to 3.

Driven by westward flowing upper level trade winds, and powered by their extreme internal energy derived from hot air condensation, hurricanes move across the Atlantic toward North and South America.

Depending on interactions with air masses on the continents or the open ocean, (westerlies) hurricanes will frequently be blocked or deflected northward and may or may not make landfall. Hurricanes which do manage to impact land, do so in

an unforgettable way!

It is helpful to look at the map below which plots the worldwide distribution of the paths of major cyclones (hurricanes) during the last 150 years. By far, the South Pacific and the west coast of Central America are more often targeted by hurricanes than the Atlantic Basin. Relatively few form in the Southern Hemisphere.

What is the origin of HURRICANES?

Where would TYPHOONS form and impact?

In what area of the world would CYCLONES form and impact?

What prevailing winds might influence an Atlantic Hurricane from making landfall?

By far, which hemisphere is most targeted by hurricanes?

El Niño is observed when the easterly trade winds, which usually drive the warm waters westward, weaken, allowing warmer waters of the western Pacific to migrate eastward and eventually reach the South American Coast. The cool nutrient-rich sea water normally found along the coast of Peru is replaced by warmer water depleted of nutrients, resulting in a dramatic reduction in marine fish and plant life.

El Niño is a warm water surface current appearing annually around Christmas time along the coast of Ecuador and Peru and lasting a few weeks to a month or more.

El Nino Neutral

El Nino Southern Oscillation

La Niña is characterized by unusually cold ocean temperatures in the Equatorial Pacific, compared to El Niño, which is characterized by unusually warm ocean temperatures in the Equatorial Pacific. El Niños were

present 31% of the time and La Niñas 23% of the time from 1950 to 1997, leaving about 46% of the period in a neutral state. The frequency of El Niños has increased in recent decades, a shift being studied for its possible relationship to global climate change.

In a La Nina year, the easterly trade winds are unusually stronger than average, blowing all the warm surface water to the south pacific, drawing up even colder water from Antarctica off the coast of South America.

How does El Nino form?

In an ENSO neutral year, describe the water off the west coast of South America, near Peru and Ecuador.

What are the ramifications of an El Nino event on the biodiversity and overall health of the ecosystem in the region described above?

How does a La Nina differ from an El Nino event?

Which event is most common?

On the positive side, El Niño can help to suppress Atlantic hurricane activity. In the United States, it typically brings beneficial winter precipitation to the arid Southwest, less wintry weather across the North, and a reduced risk of Florida wildfires.

El Niño’s negative impacts have included damaging winter storms in California and increased storminess across the southern United States. Some past El Niños have also produced severe flooding and mudslides in Central and South America, and drought in Indonesia.

The consequences of an El Nino

year

The consequences of a La Nina

year

GLOBALWeather

Patterns

Neutral conditions persist with a slight hint of a coming La Nina as seen here, with the tiny expanse of below-average sea surface temperatures (SSTs) across the eastern equatorial Pacific Ocean

Climate prediction center says that the neutral conditions will continue through the summer of 2014.

What type of Winter can we expect this year, as a result?Slightly warmer and wetter…

This data represents departures from normal.

However, this is due to a stronger than normal jet. We could see a few severe outbreaks…more chance of snow, and especially ice. (Greatest chance of precipitation in Jan and Feb)

Just like the opening…this is Jeopardy! I will give you the answer, and you must write the question, phrased as they do in Jeopardy. “What is…?” You have 20 seconds for each question, and you MAY use your notes.1.The scale by which hurricane intensity is measured

2. Typical cyclonic storm originating off of the western coast of Africa.

3. The high speed, high altitude air current which most influences North America

4. Air circulation cell which forms between ITCZ and 30° North and South Latitude

5. Region in our atmosphere where Jet streams form