Download Pressure and Prevailing Winds

1. How many inches of rain does Manitou Springs receive in
May?
2. What is the highest average temperature?
3. Is there more precipitation in the winter or summer months?
Warm-up: Wednesday
1. What is the name of the prevailing
winds in the mid-latitudes?
2. Why do coastal areas have a milder
climate than inland areas?
3. What kind of weather can you expect
with high atmospheric pressure?
Warm-up:
• El Nino reading and questions
• 1. What is the name of the prevailing winds in the midlatitudes?
• 2. How does the wind affect the Earth’s energy balance?
• 3. Why do coastal areas have a milder climate than
inland areas?
• 4. What keeps Europe from being much colder than it is?
• 5. Which side of a mountain is the dry or desert side?
Factors that Affect Climate
“LACEMOPS”
The Atmosphere
• Review:
– Earth’s atmosphere is the envelope of gases
that surround the Earth.
Weather and Climate
• Weather – condition of the atmosphere at
a given time and place
• What is San Antonio’s weather like today?
• Climate – weather conditions in a
geographic region over a long period of
time
• What is the climate of San Antonio?
Factors that affect climate:
Latitude
• The most important factor
• Farther from the equator = the colder it
gets
• Direct rays of the sun always between the
tropics
Factors that affect climate:
Air Masses
• Cold air comes from the polar regions
• Hot air comes from the tropics
Factors that Affect Climate:
Continentality
Continentality
Water heats and
cools more slowly
than land, making
coastal areas milder
than inland areas
Kansas City has much colder winters and
much warmer summers than San
Francisco.
Continentality
Factors that affect climate:
Elevation
• Elevation – height on Earth’s surface
above sea level
• An increase in elevation causes a
drop in temperature
–Drops 3.5 degrees F per 1,000 ft
• Can there be snow in places that
are on the equator?
Snow on the Equator
Snow near the equator
Factors that Affect Climate:
Mountains
• Orographic effect
–Moist air pushes against a
mountain
–The air is forced to rise
–This creates clouds and causes
precipitation
Mountains: Orographic Effect
Mountains: Orographic Effect
Windward side: side of mountain facing the
wind
Mountains: Orographic Effect
• Leeward side: side of mountain facing
away from the wind
• Leeward side is called a rain
shadow.
Factors that affect climate:
Ocean Currents
• Ocean Currents – rivers of seawater
that flow in a circular path
–Created by Earth’s winds, rotation,
and the temperatures of the water
Ocean Currents
Help maintain Earth’s
energy balance
How?
• Moves heat back and forth
between the tropics and
the polar regions
• Warm currents carry heated water
from the tropics toward the cooler
middle latitudes
Gulf Stream
Warm current off the coast of Florida
flowing north to Europe
Gulf Stream
• What North American country is along
the same latitudes as Western
Europe?
• Without the Gulf Stream,
temperatures in Western Europe
would be lower
California Current
• Cool current
• Southward flowing off the west coast of
the U.S. that cools the land nearby
California Current
Factors that affect climate:
Pressure and Prevailing Winds
• the air in our atmosphere has weight
• air around you is pushing on you
Atmospheric Pressure
• High Pressure
– Cold air; dense, therefore it sinks
– As it sinks, the air heats and dries
– Usually brings stable, clear and dry weather
– can equal extreme heat and bitter cold
(Think about a hot summer day here in San
Antonio)
H
Clear Day
Atmospheric Pressure
• Low Pressure
• when air is heated, it expands, becomes
less dense, and rises
• The water vapor the air carries may
become clouds
• Brings unstable weather
Atmospheric Pressure
• Effects on weather can vary in intensity:
slight breezes and cloud cover to powerful
storms w/ heavy rain and high winds
L
Factors that affect climate:
Prevailing winds
• Air pressure affects global wind patterns
• wind always flows from high to low
pressure
Winds
• prevailing winds – winds that blow from
the same direction most of the time
• doldrums – areas with no prevailing
winds (area has little wind = problems for
sailing ships)
Kon Tiki
• https://www.youtube.com/watch?v=yS2Aq
uqLU-g
Winds
• In the middle latitudes, the prevailing
winds are called westerlies (flow from
west to east)
• In the contiguous U.S. , these winds
carry most weather patterns and storms
from the west to the east
• Contiguous – connecting or bordering
Pressure and Wind Systems
Earth’s Energy Balance: Winds
Think of Earth as a living organism, always
trying to reach a balance
*winds move heat and cold across the
earth’s surface
Factors that affect climate:
Storms
• When hot air masses and cold air masses
collide = storms
• MORE to come next week!
Factors that affect climate
Latitude
Air masses
Continentality
Elevation
Mountains
Ocean currents
Pressure and prevailing winds
Storms
El Niño and La Niña
• El Niño—Ocean and weather pattern in
which the southeastern Pacific Ocean is
warmer than usual, affecting regional
climates
• La Niña—An ocean and weather pattern
that causes the eastern Pacific Ocean to
be colder than normal
Normal
El Niño
El Niño: Cause and Effect
• Cause:
– Change in the ocean’s surface temperature
• Effect:
– Changes in weather patterns around the
world
Cause and Effect
• Cause:
– Atmospheric pressure north of Australia rises
• Effect:
– Trade winds weaken
Cause and Effect
• Cause:
– Trade winds weaken
• Effect:
– Warm water flows eastward
Cause and Effect
• Cause:
– Warm water flows eastward, over the cooler,
nutrient-rich waters off the Peruvian coast.
• Effect:
– Sea life suffers from lack of nutrients,
fishermen cannot catch any fish.