Environmental Science
Name: ______________________________
Atmosphere and Climate
Goal: The student will explain why different parts of the Earth have different climates and explain what causes
the seasons.
Vocabulary:
1. El Nino –
2. La Nina –
Notes: Chapter 7.4: Climate
Ocean Circulation Patterns
• Ocean currents have a great effect on climate because water holds a large amount of heat
• Movement of surface ocean currents is a result of winds and rotation of Earth
• Oceans make climates more moderate; coastal areas usually have warmer winters/cooler summers
• Coastal areas will usually get more precipitation than inland areas
El Nino – Southern Oscillation
 El Nino is the name given to the short-term (6 – 18 month period) periodic change in the location of warm and
cold water masses in the Pacific Ocean; weak western Pacific Ocean winds strengthen and push warm water
eastward; rainfall follows the warm water eastward and produces increased rainfall in the southern half of the US
and in equatorial S. America; drought in Indonesia and Australia
 During La Nina, water in the eastern Pacific Ocean is cooler than usual
 El Nino and La Nina are opposite phases: El Nino is the warm phase of the cycle and La Nina is the cold phase
Pacific Decadal Oscillation
 This is the long term (20-30 year) change in the location of warm and cold water masses in the Pacific Ocean.
 Influences the climate in the northern Pacific Ocean and North America
 Affects ocean surface temperatures, air temperature and precipitation patterns
Topography
• Latitude does affect climate; however, height above sea level also has an effect on climate. Ex: Mt. Kilimanjaro
(Tanzania) is 3° south of the equator but has snow covered peaks year round
• Plants and animals living in the mountains will resemble those living in cold, northern climates
• Mountains and mountain ranges also affect precipitation ex: Sierra Nevada mountains (California) – coastal side
is very moist and receives a great deal of rain; the eastern side is the Great Basin Desert; this effect is called a rain
shadow
Other Influences on Earth’s Climate
 Both sun and volcanic eruptions influence Earth’s climate; at a solar maximum the sun emits an increased amount
of UV radiation, producing more ozone; this increase warms the stratosphere as well as the lower atmosphere and
surface of the Earth
 Large-scale volcanic eruptions spews sulfur dioxide into the upper atmosphere, which can remain there for up to 3
years; it reacts with smaller amounts of water vapor and dust forming a bright layer of haze that reflects enough
sunlight to cause global temperatures to decrease.
Seasonal Changes in Climate
• Temperature and precipitation change with the seasons, but what causes the seasons? The Earth’s orbit around
the sun and the tilt on its axis
• During spring and summer in the Northern Hemisphere, it is tilted toward the sun, receiving more concentrated,
direct sunlight; Southern Hemisphere is tilted away receiving less concentrated sunlight. During fall and winter,
the situation is reversed
•
Our four seasons do not occur in the tropics (close to the equator); they have high constant temperatures
throughout the year and receive the most direct sunlight year round
Lesson Reflection:
Using the picture of the world map and the overhead of the surface water temperatures for the world, to
the best of your abilities, color in the map showing where the surface water is warm and where it is cool. Be
sure to include a key.
Assessment:
1. What is the difference between El Nino and La Nina?
2. Explain what causes the seasons.
Active Reading: Climate and Climate Change
Lesson Extension (Technology/Application/Connection to Real World):
Watch PBS video: The Ocean and Weather: El Nino and La Nina (3:00 min)