Download weather and oceanography

Enduring Understanding
• Energy transfer between the Earth’s surface
and the atmosphere creates the weather.
• The atmosphere remains in balance until
acted on by an outside force.
Weather
– Weather is the current state and short term
variations in the state of the atmosphere
• Takes place over minutes, hours, days, weeks,
months
Causes of Weather
• Climate is the long term variations for a
particular area
– Averaged over 30 years or more of weather data
Redistribution of Wealth
• Without the atmosphere this energy
imbalance would continue and the tropics
would be very hot and the poles very cold
year round
– The oceans store the majority of heat at Earth’s
surface
Redistribution of Wealth
• Temperature differences in the air result in
differences in density which the cause upward
and downward movement
• The convection currents of the atmosphere
redistribute the heat energy as air over the
warmer regions rises, cools, then descends
over cooler regions.
Redistribution of Wealth
• This movement causes weather
Air Masses
• An air mass is a large body of air that takes on
the characteristics of the body over which it
forms. They can form over either land or
water and are classified according to their
source regions
Air Masses
• Continental Tropical (cT) air masses contain warm,
dry air that forms over warm areas of land
• Maritime Tropical (mT) air masses contain warm,
humid air that forms over warm areas of the ocean
• Continental Polar (cP) air masses contain cold, dry
air that forms over cold areas of land
• Maritime Polar (mP) air masses contain cold, humid
air that forms over cold areas of the ocean
• Arctic (A) air masses are basically the same as cP, but
much colder and are associated with extreme cold
North American Source Regions
• All five main air mass types can be found in
North America because of our close proximity
to the source regions associated with each
type of air mass
North American Source Regions
• Continental Tropical (cT) air forms over the
desert of the southwest United States and
Mexico
North American Source Regions
• Maritime Tropical (mT) air forms over the
southern Atlantic, Gulf of Mexico, and
southern Pacific oceans
North American Source Regions
• Continental Polar (cP) air forms over the
interior of Canada and Alaska
North American Source Regions
• Maritime Polar (mP) air forms in the northern
Pacific and Atlantic oceans
North American Source Regions
• Arctic (A) air develops over the extreme
northern regions of the continent
Stability and Air Mass Movement
• Air masses do not stay in one place
indefinitely. They move and transfer their
heat from one area to another establishing a
balance of heat throughout the planet
Stability and Air Mass Movement
• Air mass modification occurs when the
moving air mass changes to become more like
the surface over which it travels
• Heat and moisture are exchanged with the
surface as the air mass travels over it
Stability and Air Mass Movement
• Eventually the air mass will become modified
to the point it is indistinguishable from the
new surface over which it is traveling and
simply becomes part of the air over the new
source region
Coriolis effect
• The Coriolis Effect on Earth causes moving
particles (air molecules ) to deflect to the
right in the northern hemisphere and to the
left in the southern hemisphere
Global Wind Patterns
• Trade Winds occur at where the warm, rising
air from the equator begins to cool and sink.
They occur below 30 degrees latitude and
blow in an east to west direction
Global Wind Patterns
• Prevailing Westerlies flow between 30 and 60
degrees latitude and blow from west to east. This
pattern is responsible for much of the weather in
North America
Global Wind Patterns
• Winds are named for the
direction they blow from
Global Wind Patterns
• Polar Easterlies blow from east to west
between 60 deg and the poles and are
characterized by very cold air
Global Wind Patterns
Jet Streams
• Often the weather report will state that the
jet stream is affecting today’s forecast in some
way. Earth weather is strongly influenced by
atmospheric conditions and events between
the wind zones
Jet Streams
• Jet Streams are narrow bands of fast, highaltitude, westerly winds and flow at speeds of
185 km/hr
• Their position varies and drives large-scale
weather systems
Fronts
• Since air masses of different characteristics
are constantly in motion some of them are
bound to eventually collide
Fronts
• Front is the narrow region separating two air
masses of different densities
• Density differences are caused by differences
in temperature, pressure, and humidity
Fronts
• There are four main types of fronts and the
interaction of colliding air masses often causes
dramatic changes in weather
Fronts
• Cold Fronts occur where cold, dense air
displaces warm air and we see clouds,
showers, and thunderstorms
Fronts-Cold Front
Generally, with the passage of a cold front, the temperature
and humidity decrease, the pressure rises.
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Cold Front-crossing NYS - October 2008 (metars
and satellite)
Fronts
• Warm Fronts are where advancing warm air
displaces cold air and we see extensive
cloudiness and precipitation
Fronts-Warm
Generally, with the passage of a warm front, the
temperature and humidity increase, the pressure
decreases.
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Fronts
• Stationary Fronts are where the two air
masses meet but neither advances. Little
cloudiness and precipitation is seen
Fronts
• Occluded Fronts occur where a cold air mass
overtakes a warm front and wedges it
upward. It then collides with another cold
front and causes precipitation on both sides
Fronts-Occluded
Occluded front is formed when a cold front
overtakes a warm front.
Pressure Systems
• The vertical movement of air combined with
the coriolis effect results in the formation of
rotating low and high pressure systems
High Pressure System
• High Pressure Systems are formed by dense,
sinking air and move in a clockwise direction
(in the northern hemisphere)
– High pressure is associated with fair weather
Low Pressure Systems
• Low Pressure Systems form by low density
rising air moving in a counterclockwise
direction
– Low pressure is associated with stormy weather
Analyzing/Forecasting Weather
• In order to accurately analyze and forecast
weather meteorologists must be able to
reliably gather the necessary data about the
atmosphere. The quality and amount of data
available for a certain location greatly affect
the outcome of the forecast
The Instruments of Meteorology
• Thermometer measures temperature.
– They usually contain liquids such as mercury or
alcohol that expand when heated
The Instruments of Meteorology
• Barometer measures air pressure. The
common types are mercury and aneroid
The Instruments of Meteorology
• Psychrometer measures relative humidity. A
wet and dry bulb thermometer is the most
common type
The Instruments of Meteorology
• Anemometer measures wind velocity. The
simplest type has cupped arms that rotate as
the wind blows
Technology in Meteorology
• The accuracy of weather forecasting has
greatly improved over the last 40 years. Many
technological advances from other sciences
have been found to have practical applications
in Meteorology
Technology in Meteorology
• Weather Radar allows us to track real-time
movement of precipitation inside the
coverage area.
– Today most of the United States is covered by one
or more weather radar sites
Technology in Meteorology
Technology in Meteorology
• Weather Satellites take photographs and
other images of the Earth’s surface at regular
intervals.
Imagery
– These images are plotted and combined with
radar data to determine where both clouds and
precipitation are occurring
Technology in Meteorology
• Infrared Imagery is allows us to see
temperature differences in the surface and
moving air masses and allows us to predict a
systems potential to produce severe weather
Weather Analysis
• Once the weather observations are gathered meteorologists
plot the data on a map using universally recognized symbols
for the various pieces of information to be represented
Weather Analysis
• Station model is a record of the weather data
for a particular site at a particular time and
allows a large amount of data to be plotted in
a small space
Large Scale Weather Plotting
• Once the information for individual sites is plotted
meteorologists can construct large scale (nationwide
or worldwide) weather maps that represent the
current state of the whole troposphere
Large Scale Weather Plotting
• Isopleths are lines that connect equal or
constant values and are similar to the contour
lines used in geography
– Isobars connect areas of equal air pressure
Large Scale Weather Plotting
– Isotherms connect areas of equal
temperature
Short Term Forecasting
• Weather forecasting has improved much over
the past few decades and continues to do so
as we advance in our ability to obtain and
process weather data
Short Term Forecasting
• Digital Forecasts are the main method used by
modern meteorologists. They rely on
numerical data and are highly dependent on
the density of data available. The more
(accurate) data the more reliable the forecast
Short Term Forecasting
• Analog Forecasts compare current weather
patterns to those that took place in the past
– The Farmers Almanac is an analog forecast
Long Term Forecasting
• Regardless of the method used all forecasts
become less reliable when they attempt to
predict long term weather. Even high tech
supercomputers cannot account for every
factor that influences the weather and
miscalculations are compounded with time
Origin of the Oceans
• Several geologic clues indicate that the oceans
have existed almost since the beginning of
geologic history
Origin of the Oceans
• There are two general hypotheses about the
origin of the Earth’s oceans
Origin of the Oceans
#1
• Comets and meteorites that impact the planet
and release water
Origin of the Oceans
• Meteorites generally contain 5% water
Origin of the Oceans
#2
• Volcanism early in Earth’s history released
significant amounts of water vapor among the
other gasses to form the early atmosphere
Origin of the Oceans
• The water vapor cooled and condensed to
form the oceans
Distribution of Oceans
• The oceans contain 97% of Earth’s water
Distribution of Oceans
• Sea Level is the level of the ocean’s surfaces
and has risen and fallen by hundreds of meters
in response to expanding and receding glaciers
The Major Oceans
• The oceans cover 71% of Earth’s surface. The
landmasses are like islands completely
surrounded by water.
Oceans
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•
•
•
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The five major oceans are
Pacific
Atlantic
Indian
Arctic
Southern (ANTARCTIC)
Seawater
• The water of the world’s ocean is undrinkable.
Seawater is a solution of about 96.5% water
and 3.5% dissolved salts
Chemical Properties of Seawater
• Salinity is the measure of the amount of
dissolved salts in seawater
Chemical Properties of Seawater
• Salinity can vary between 3.2% and 3.7%
depending on location, precipitation and
temperature
Seawater
• Although sodium and chloride are the most
abundant nearly all naturally occurring
elements on Earth (including gold and silver)
are found dissolved in seawater
The Seafloor
• Continental margins are the submerged parts
of the continents and are the shallowest parts
of the oceans
The Seafloor
• They include the continental shelf, and
continental rise
The Seafloor
• Continental Slope
The Seafloor
• and Continental Rise
The Seafloor
• Ocean basins lie beyond the continental
margins and contain the abyssal plains
The Seafloor
• Deep-sea trenches
The Seafloor
• Mid-Ocean ridges
• http://www.wwnorton.com/college/geo/ocea
nsci/animations.asp
The Seafloor
• and Hydrothermal vents