by Paul Nervy
Copyright (c) 2006 by Paul Nervy
Visit www.paulnervy.com.



History of earth sciences



Air is a gas made mostly of nitrogen, hydrogen, oxygen and carbon dioxide.  Air also contains water vapor.

The atmosphere is the layer of air around the earth.

Levels of the atmosphere
Troposphere.  Closest to ground.  Up to 7 miles.
Stratosphere.  Up to 30 miles.
Mesosphere.  Up to 50 miles.
Ionosphere or thermosphere.  Up to 400 miles.

Ozone blocks harmful ultraviolet rays.  The ozone layer is being depleted by humans.


Global weather forces

The weather is the result of changes in the temperature, humidity and pressure of air, which cause wind and precipitation.  

The earth is a rotating sphere with an outer layer of atmosphere.  The movement of air in the atmosphere is three dimensional. 

The position of the sun, contients and oceans also have an effect on the weather.

The tilted axis of the earth causes the seasons by affecting the hours of sun received per day.  When the earth is tilted toward the sun the days are long and warm.  When the earth is tilted away from the sun the days are short and cold.

The sun heats the earth.  The atmosphere's winds and the ocean's currents carry heat from the equator to the poles.

Air at the poles is cooler and drier.  Air at the equator is warmer and holds more moisture.

Cold air moves from the poles toward the equator.  Warm air moves from the equator toward the poles.

At any given altitude, warm air rises and cool air sinks.  That is why hot air balloons rise.  That is why the basement of a house is cooler than the attic. 

At any given location, air gets heated during the day and cools at night.  This heating and cooling can cause winds.

Air tends to move from areas of high pressure to areas of low pressure

Air tends to picks up moisture over water and losses moisture over land.

Increase in lattitude causes colder weather, and that is why its usually colder in the northern lattitudes.

Increase in altitude causes colder weather, and that is why its usually colder on the top of a mountain than in the valley.

Air masses
Maritime polar (mP) - a wet, cold air mass.
Continental polar (cP) - a dry, cold air mass.
Maritime tropical (mT) - a wet, warm air mass.
Continental tropical (cT) - a wet, dry air mass.  

The geography of continents and oceans, at varying lattitudes and at various times of the year, cause the above air mass types, which cause regular global weather patterns.

The elliptical shape of the orbit of the earth around the sun causes little effect on the weather.


Air pressure.
Air has mass and weight.  Air pressure is due to the atmosphere pressing down on the earth due to gravity.  At sea level there is a lot of air pressing down and thus much pressure.  At high altitude there is little air pressing down and thus little pressure.

Altitude and air pressure.  
As alitude increase the air becomes less dense, colder, and holds less moisture.  Closer to sea level the air is more dense, warmer, and can hold more moisture.  

Humidity and air pressure.  
Water vapor in the air increases the mass of the air.  Humid air has more moisture and thus exerts more pressure.  Less humid air has less moisture and exerts less pressure.

Temperature and air pressure.  
High pressure heats up air, low pressure cools air, and that is why the temperature of the air decreases as one gains altitude from sea level to the stratosphere.

Wind and air pressure.
A barometer measures changes in vertical air pressure due to the density of the atomospher, not changes in horizontal air pressure due to wind.  Wind has a pressure all its own.  

If altitude and temperature are constant, then humidtity
If altitude and humidity are constant, then temperature
If humidity and temperature are constant then altitude

A barometer measures air pressure.  A barometer consists of a column of mercury in a glass tube.  A drop in the barometer reading indicates a storm approaching because there is more humidity in the air which increases the chance of precipitation.  A rise in the barometer reading indicates clearing weather because there is less humidity in the air which means less chance of precipitation.

A confusion is that often when people refer to "high pressure areas" and "low pressure areas" they are really referring to the reading of the mercury on the barometer, not the amount of pressure exerted by the air.

If a barometer measures change in air pressure caused by change in water vapor then why not measure the humidity?

An altimeter measures altitude, usually by measuring the change in barometric pressure as one ascends or descends, assuming that there is no change in the barometric pressure due to changes in the weather.  

Is air pressure related to altitude like water pressure is related to depth of water?  Yes.  Higher altitudes have less air pressure?  If so, then why does air pressure vary at a fixed altitude?

How does air pressure vary with temperature?  Does warm air have a higher or lower air pressure than cold air?

Air pressure.  
The composition of air does not change much.  So for any given temperature and altitude, the only way the air can have be heavier, and exert more pressure downward, and cause a lower barometer reading, is if there is a greater percentage of water vapor in the air, which also causes a higher humidity reading.  

Air pressure downward when there is no wind.
More pressure at sea level.  Less pressure at altitude.

Humidity and air pressure.
Warmer air holds more water vapor and that humidity causes more air pressure?  

Wind and air pressure.
Does moving air, i.e., wind, have greater air pressure than stationary air?


Air Temperature.  

Air temperature drops as you gain height.  What causes that phenomenon?

Air temperature is also related to geography.
Temperatures are hotter at the equator and cooler at the poles.
Cold air from poles.  
Warm air from equator.

Warm air holds more moisture than cold air.
Warm air is more dense than cold air.


Air humidity.  

What is the lowest humidity?  A low humidity day on east coast is 30%.

Warm air holds more moisture than cold air.  Air is colder the higher you go up in the atmosphere.  Therefore, most of the moisture in the air is at the surface of the earth.

Humidity and precipitation.
Precipitation is more likely if the humidity is high.


Air temperature, air pressure, humidity, and altitude.

Low altitude air is warmer than high altitude air.
Low alititude air has more moisture than high alititude air.
Low altitude air has more pressure than high altitude air.



Warm front
A warm front is a mass of warm air moving into a mass of cold air.  Warm air slips above cold air.

Cold front
A cold front is a mass of cold air moving into a mass of warm air.  Cold air pushes warm air up.

Stationary front.
A stationary front is when two air masses are side by side with little movement.

Occluded front.
An occluded front displays attributes of a cold front and a warm front.

What causes warm fronts and cold fronts to push each other around?
Changes in pressure?


Wind is the motion of air around the planet.

Wind is not caused by the earth rotating beneath the atmosphere.  The atmosphere rotates with the earth.

How is wind formed?  
Movement of hot and cold air, vertically and horizontally.
Air moves from areas of high pressure to low pressure.

Local wind is caused by movement of air near fronts?

What causes wind?
	The rotation of earth.  No.
	The interplay of warm and cold fronts.
	The air can't just sit still everywhere all the time.

The atmosphere experiences convection on a global level.

Coriolis effect.
Air is heated near the equator.  It rises and moves toward the poles.  

Flow of wind from west to east.  Due to rotating earth?  No.  Why doesn't the atmosphere rotate too?  It does.

Global winds

The doldrums are an area of calm near the equator.

Trade winds
Trade winds are winds around 30 degrees lattitude that flow east to west.  Trade winds are good for sailing east to west. 

Westerlies are winds around 45 degrees lattitude that flow west to east.  Westerly winds are good for sailing west to east.

Hadley cells
Hadley cells are air movements that circulate from the equator diagonally to about 30 degrees lattitude.

Jet stream
The jet stream are high altitude, high speed winds.

Cyclones are low pressure areas where the wind spirals downward in a counterclockwise direction in the northern hemisphere and clockwise direction in southern hemisphere.

Anti-cyclones are high pressure areas where the wind spirals upward in a clockwise direction in the northern hemisphere and counterclockwise direction in the southern hemisphere

Local Winds

Chinook is a hot, dry wind in Rocky Mountains, US.

Santa Anna winds are a hot, dry wind from the Sierra Nevada mountains toward the Pacific Ocean in California, US.

Canadian clipper is a cool, dry wind from Canada towards the United States.

Nor'easter is a storm that travels up the eastern seaboard of the United States.

El Nino is a weather phenomenon caused by a shift in Pacific Ocean currents.

Mistral is a hot, dry wind in France.

Foehn is a hot, dry wind in in Germany.

Harmattan is a hot, dry wind in north Africa.

Monsoon is a wet wind in India.



Clouds are aggregations of water vapor.

What holds clouds together?  Why doesn't the water vapor disperse into the general humidity level?

How do clouds form and then disperse?

Types of clouds.  

Stratus clouds are low level and like a blanket.

Cumulus clouds are mid height and puffy.

Cirrus clouds are high and wispy.

Nimbus clouds are rain clouds.




Storms and Precipitation.  

What causes tornadoes?

Hurricanes.  Typhoons.
What causes hurricanes?
Why is there a hurricane season?

Lightning is discharge of static electricity that builds up in clouds.

Thunder is the sound made when a lightning strike occurs.

Rain is caused when water vapor condenses out of clouds.

Sleet is freezing rain.

No two snow flakes are alike.

A blizzard combines snow, wind and low temperatures.

Hail is precipitating ice balls that can be as large as softballs.


Fog is similar to clouds.  Fog is clouds at ground level.

Dew is usually found in the morning.  Dew is caused by condensation.  

Aurora Borealis.
Aurora Borealis is a colorful display at night caused by solar activity.

Sprites, ELVES and blue jets.
Sprites, ELVES and blue jets are electromagnetic disturbances in the upper atmosphere.

Weather forecasting.
The history of weather forecasting.
Heuristics.  Weather sayings.  Weather folklore.  Based on clouds.  Based on wind direction.
Weather record keeping.
Scientific weather observation.  Exact, daily measurement of temperature, humidity, precipatation, etc.
Weather observatories linked by communications technology.  Knowing what weather is headed your way.
Statistical analysis of weather data.
Automation of weather observation.
Computerization of weather forecasting.  Computer forecasting models.
Weather reports on the news.
More accurate and longer range weather forecasts.

Human effects on the weather.
Acid rain.
Greenhouse gases and global warning caused by increased carbon dioxide levels.

Dew point.  
The dew point is the condensation point, or the temperature at which water vapor turns from a gas to liquid.  The dew point temperature changes depending on the humidity of the air.  High humidity causes a low dew point.  Low humidity causes a high dew point.

Wet bulb
A wet bulb is a thermometer whose bulb is wrapped in wet cloth.  The wet bulb measures humidity.  The wet bulb reading is similar to the heat index.

Heat index
The heat index is a measurement that combines temperature and humidity.  The heat index is a "real feel" reading.

Wind chill.  
The wind chill is a measurement that combines temperature and wind speed.  The wind chill is a "real feel" reading.

Daily weather phenomena
Many mountain ranges recieve afternoon thunderstorms due to the change in temperatures between day and night.

Seasonal weather phenomena

Year round weather phenomena







Hardwater.  Many minerals.
Softwater.  Rainwater.  Mineral free.


Lakes and ponds

Lakes have a life cycle.  Lakes can eventually turn into meadows.


Rivers and streams.

Rivers meander into tight curves, due to the forces of the flowing water.



Polar ice caps



Freshwater wetlands.  Marshes.  Swamps.

Saltwater wetlands.  Mangrove swamps.  Estuaries.  Tidal pools.  Bays.


Coral reefs.



Ocean waves.

Ocean currents.  Do the major ocean currents mimic the major air currents?

Ocean water layers.

Ocean water temperatures.  Deeper water is colder.

Ocean water pressure.  Deeper water has more pressure, measured in pounds per square inches.

Ocean salinity.  Why is the ocean salty?  

Ocean evaporation. 

Ocean tides.

Tides are caused by revolution of the earth which occurs once every 24 hours and its relation to the moon.

High tide.

Low tide.

The revolution of the moon around the earth occurs once a month and this causes additional tidal effects.

The oceans have some similarities to the atmosphere in that it is a three dimensional fluid (flowing) environment.  There are differences as well.

Water temperature decreases as you go down.  (Opposite of atmosphere)

Water pressure increases as you go down.  (Similar to atmosphere)

Water movement
There is a vertical movement of water.  Cyclical.
There is a horizontal movement of water.  Currents.

But cold water sinks.  Warm water near surface.  (Opposite of atmosphere)





The Earth.

The Earth is a planet.

How old is the earth?  About 4 billion years old.

How did the earth form?  Planets, like Earth, form when rocks in space gather due to force of gravity.


Plate tectonics theory.
There are appoximately ten large tectonic plates covering the earth.  The seams where the plates meet often experience earthquakes and moutain building.  

Continental drift.
The continents are drifting.  Proof includes:  (1) The outline of north and south america match the outline of europe and africa.  (2) Similar rocks are found on the edges of continents across the oceans.  (3) Identical fossils are found in the rocks.

Years ago the continents were closer than today.

Years ago the continents were closer than today.

Sea floor spreading.
Harry Hess noticed the sea floor is not flat and covered with hundreds of feet of sediment.  The sea floor has mountains and valleys.  The sea floor is spreading out.



Mountain building.
Mountain building occurs where the tectonic plates meet.

Two processes.
Mountain building.
Erosion.  Wind erosion.  Water erosion.

Mountain building theories.
Catastrophism vs. uniformatism. 




Some volcanic eruptions.  
Krakatoa.  Indonesia.  
Mt Vesuvisu.  Pompeii, Italy.  
Mt. St. Helens.  Washington, USA.  
Mount Pinatubo.  Phillapines.
Hawaiian volcanoes.  Hawaii, USA.


Richter scale.

Some earthquakes.
1906.  San Francisco, California.
1976.  Tangshan, China.
1964.  Anchorage, Alaska.
1995.  Kobe, Japan.


Magnetic field of earth.
The earth has a magnetic field and it shifts periodically.

Geological convection.




Soil = sand + clay + organic material
Soil takes years to make, yet is quickly eroded by wind and rain.

Rock.  Bedrock.

Structure of eath.
Core.  Molten rock.  Hot.
Mantle.  Rocky.  Cooler.

Age of the earth - 4 billion years old



Igneous.  Ex., granite.

Sedimentary.  Ex., limestone.  Sandstone.

Metamorphic.  Ex., schist, shale, slate.




Found in the earth, and extracted by mining.



Gemstones.  Diamonds.  Emeralds.  Rubies.  Sapphires.  Topaz.  Onyx.  

Metal ores.  Metals.  Gold.  Silver.  Copper.  Iron. 

Radioactive elements.  Uranium.

Moh's scale of rock hardness

Magnetic fields of the earth.


Ice ages.

Snowball earth theory.
Snowball earth theory holds that at some point in its history the Earth experienced a drop in temperature until the Earth was completely covered in ice.


View of the earth as flat.  (wrong)
View of the earth as round.  (correct)
View of the earth as a solid sphere.  (wrong)
View of the earth as a hollow sphere.  (wrong)
View of the earth as having layers, some liquid.  (correct)


History of Earth Science (see history database)


What causes tides?  
Moon moving around earth?  No, that occurs once a month.  
Earth spinning every 24 hours, and thus moon pulling every 24 hours?  Yes, that it.

What causes phases of moon?  
The earth goes around sun once a year.  That has little effect.
The earth rotates on its axis once a day.  That has little effect.
The moon revolves around earth once a month.  That has a big effect.
	When the earth is between the sun and moon, it looks like a full moon.  
	When the moon between the 
	When the moon 

Year.  Earth around sun.

Night and day.  Spinning of earth on its axis.