What is meteorology? A. METEOROLOGY: an atmospheric

science that studies the day to day changes in the atmosphere 1.  ATMOSPHERE: the envelope of

gas that surrounds the surface of Earth; the air

2.  WEATHER: the day to day changes in the atmosphere caused by shifts in temperature, air pressure, and humidity

B.  Meteorologists are scientists that study atmospheric sciences that include the following: 1.  CLIMATOLOGY: the study of climate 2.  ATMOSPHERIC CHEMISTRY: the

study of chemicals in the air 3.  ATMOSPHERIC PHYSICS: the study

of how air behaves 4.  HYRDOMETEOROLOGY: the study

of how oceans interact with weather

What is the atmosphere? A. The earth’s atmosphere is

made of air. 1.  Air is a mixture of matter

that includes the following: a.  78% nitrogen gas b.  21% oxygen gas c.  0.04% carbon dioxide d.  0.96% other

components like water vapor, dust, smoke, salt, methane, etc.

2.  The atmosphere goes from the Earth’s surface to 700km up.

3.  The atmosphere is divided into 4 main layers as one ascends.

What is the atmosphere?

a.  TROPOSPHERE: contains most air, where most weather occurs, starts at sea level

b. STRATOSPHERE: contains the ozone layer that holds back some UV radiation

c.  MESOSPHERE: slows and burns up meteoroids

d.  THERMOSPHERE: absorbs some energy from the sun

What is the atmosphere? B. The concentration of

air in the atmosphere increases the closer one gets to sea level. 1.  The planet’s

gravity pulls the atmosphere against the surface.

2.  Air above pushes down on air below, causing a higher concentration in the troposphere.

What are the major factors that impact weather? A.  There are four major factors that influence

weather on a daily basis: 1.  TEMPERATURE: the level of heat

energy in the air 2.  AIR PRESSURE: the amount of

pressure (weight) the air exerts due to the concentration of air

3.  WIND: air that moves from high to low pressure

4.  MOISTURE: the amount of evaporated water in the air

B.  All four of these factors are influence directly or indirectly by the sun’s energy : 1.  Solar energy warms the ground and air 2.  Heat causes water to evaporate 3.  When air is heated, it changes its

concentration 4.  Heated air travels to the poles while

cooler air travels toward the equator

How is temperature a major factor of weather? A.  Thesun’senergytravelsthroughspace,asmallportionreachesEarth:

1.  30%isreflectedbackintospace.2.  20%isabsorbedbytheatmosphere.3.  50%isabsorbedbyEarth’ssurface.

B.  Thesolarenergythatisabsorbedistransformedintoheatenergy:1.  Someisabletoescapetheplanet.2.  Somewarmsthelandandwater.3.  Someistrappedandabsorbedintheatmospherebygreenhouse

gaseswhichincludeCO2,H2O,andMethane.

How is temperature a major factor of weather?

C.  Parts of the Earth receive more solar energy than others due to the curvature of the Earth and its tilted axis 1. Tropical climates receive more direct energy, causing increased temperatures. 2. Polar climates receive less direct energy, causing decreased temperatures.

3.Thislockedpositionallowsfordifferentclimates,seasons,andweatherpatternsacrosstheplanet.

How is temperature a major factor of weather? D. Heat moves through the atmosphere in two ways:

1.  CONDUCTION: heated air moves from higher temperatures to lower temperatures.

2.  CONVECTION: warmer air is less dense and cooler air is more dense, warm air rises and cool air falls.

How is air pressure a major factor of weather? A.  Air is pulled down against the Earth’s surface by

gravity and pushed down by the air above it. 1.  The force of air pulled and pushed down on

the Earth’s surface gives it weight. 2.  This force is known as AIR PRESSURE. 3.  There is more air concentrated at sea level. 4.  Air gets thinner as rise up through the

atmosphere B.  Air pressure is measured as either high or low:

1.  HIGH AIR PRESSURE tends to be: a.  COOLER: cooler air is more concentrated b.  MORE DENSE: falling toward the surface c.  DRY: molecules like nitrogen, oxygen, and

carbon dioxide are heavier 2.  LOW AIR PRESSURE tends to be:

a.  WARMER: warmer air is less concentrated

b.  LESS DENSE: rising upward c.  MOIST: water molecules are lighter and

displace other molecules

air above pushes down

gravity pulls down

How is air pressure a major factor of weather? C. Air moves out from an area of high pressure to an area of low

pressure. 1.  High pressure systems are where the air is more concentrated.

a. Air in this system moves out and away from where it is most concentrated to where it is least concentrated

2.  Low pressure systems are where the air is less concentrated. a. Air in this system moves inward towards where air is least concentrated.

H L

How is wind a major factor of weather? A.  Wind is responsible for carrying heat and moisture throughout the

atmosphere: 1.  WIND: horizontal (side to side) movement of air

a.  Wind is formed when cool, heavy air moves toward warm, light air b.  Wind is also formed when high pressure air moves to regions of

low pressure air 2.  AIR CURRENT: vertical (up and down) movement of air

a.  Small vertical movements are called updrafts and downdrafts b.  Air currents are caused by uneven heating of the earth’s

surface i.  Warmer regions produce warmer air that is less dense & rises ii.  Cooler regions produce cooler air that is more dense & sinks

How is moisture a major factor of weather? A.  The movement of moisture (water) is a result of the water cycle:

1.  WATER (HYDROLOGIC) CYCLE: the repeated pattern of water movement between the atmosphere and Earth’s surface

a.  EVAPORATION: the changing of liquid (water) to gas (water vapor) due to heating 1.  TRANSPIRATION: a process in plants where liquid water

traveling through stems is then given off as water vapor through and out the leaves

2.  HUMIDITY: the level of water vapor measured in the air b.  CONDENSATION: the changing of gas (water vapor) to

liquid (water) due to cooling 1. Clouds are formed by the condensation of water vapor in

the upper parts of the troposphere where its cooler. c.  PRECIPITATION: water that falls from the atmosphere due

to a concentration that can no longer be held aloft 1. This can fall as a solid (snow/ice), liquid (rain), or mixture

d.  SURFACE /SUBSURFACE RUNOFF: the movement of liquid water through a watershed from high to low elevation

e.  ACCUMULATION: the collection of liquid water into bodies of water such as river, lakes, streams, pond, and seas

How is moisture a major factor of weather?

Cirrus Clouds Cumulus Clouds Stratus Clouds

How is moisture a major factor of weather? B. Moisture in the air, as water vapor, can rise into the upper parts of the

troposphere and condense to form clouds. 1.  CLOUD: a visible mass of condensed water vapor in the air 2.  There are three major types of clouds:

a.  CIRRUS CLOUDS: thin wispy clouds that are typically at high levels

b. STRATUS CLOUDS: layered clouds that often cover the entire sky often found at mid levels

c. CUMULUS CLOUDS: thick, puffy clouds that are flat at the base and rounded at the top often found at lower levels

How do all Four Factors Work Together? A.  When all four factors are taken

together, we have shifts in the weather. 1.  Shifts in the weather are often

a result of a large amount of air (air mass) moving into an area replacing another large amount of air.

2.  This shift from one air mass to another is called a front. There are four major types of fronts: a.  Cold Front b.  Warm Front c.  Occluded Front d.  Stationary Front

a.  COLD FRONT: cold air mass moving in to replace a warm air mass i.  Cold air is more dense and hugs the ground ii.  Cold air wedges underneath warm air forcing warm, moist air

upward; moisture condenses forming clouds and precipitation iii.  Cold fronts occur more often in early to mid spring and mid to

late fall

Cold Air Mass

Warm Air

Direction of Motion

Cold Front

Cloud Formation

How do all Four Factors Work Together?

b. WARM FRONT: warm air mass moving in to replace a cold air mass i.  Warm air is less dense and moves above the surface ii.  Warm air slides up the back of a cold air mass forcing warm

moist air upward where moisture condenses iii.  Warm fronts occur in late spring into summer

Cold Air

Warm Front

Direction of Motion

Cloud Formation

Warm Air Mass

How do all Four Factors Work Together?

c.  OCCLUDED FRONT: cold air mass moving into to replace another

cool air mass i.  Cold air overtakes and blends with slightly warmer air causing

cooling ii.  An even colder air mass behind the cool air pushes in forcing the

cool air out iii.  Occluded fronts occur in late fall and winter

Occluded Front

Cloud Formation

Cold Air Mass

Direction of Motion

Cool Air Mass

Direction of Motion

How do all Four Factors Work Together?

d.  STATIONARY FRONT: cold air mass and warm air mass opposing each other that results in little movement. i.  Neither air mass has enough energy to remove the other and

remain locked in one place ii.  These occur most often over open ocean and coastal regions

Stationary Front

Direction of Motion

Warm Air MassCold Air Mass

Direction of Motion

Cloud Formation

How do all Four Factors Work Together?

How do all Four Factors Work Together? B. Air masses that make up these fronts can originate from either over land or

sea around the United States: 1.  MARITIME POLAR (mP): cold, wet air masses that are formed out over

the northern Pacific or northern Atlantic Oceans 2.  MARITIME TROPICAL (mT): warm, wet air masses that are formed out

over the southern Pacific Ocean, southern Atlantic Ocean or Gulf of Mexico

mP

mT

mP

mTmT

How do all Four Factors Work Together? 3.  CONTINENTAL POLAR: (cP) cold, dry air masses that are formed

over the eastern or western sections of the North American Continent 4.  CONTINENTAL TROPICAL: (cT) warm, dry air masses that are

formed over Central America 5.  ARCTIC: (A) very cold, dry air masses that are formed above the

Arctic Circle and travel south over the North American continent

cP

cT

A

How do all Four Factors Work Together? C. Air masses across N. America are often moved by the jet stream:

1.  JET STREAM: narrow bands of strong winds at high altitudes that flow like rivers of air from west to east a.  Jet streams tend to form a barrier between the cold polar air and

warm tropical air b.  Jet streams run a winding path as they flow from west to east

i.  RIDGES: areas of the jet stream that angle towards the north allowing tropical air masses to move north

ii.  TROUGHS: areas of the jet stream that angle towards the south allowing polar air masses to move south

cold air mass

warm air m

ass

ridge

trough