Transcript Climate and Weather

• Learning Target:
– Understand the differences between weather and
climate as well as their causes.
• Language Objective:
– Describe the weather and climate of an area.
Climate Vs. Weather
• What is weather?
– Day-to-day conditions of the atmosphere.
• What is climate?
– Average conditions in a region.
– Includes temperature and precipitation.
– Examples:
• Desert, tropical rain forest, temperate forest, tundra
The Pacific Northwest
• Why are the seasons mild and rainy on the west side
of the mountains vs. dry and more extreme seasons
over on this side?
– Orographic Rainfall
• Water that evaporates into the atmosphere on the west side
(windward side) hits the Cascade Mountains and forms clouds
through condensation as it cools at higher altitudes. Clouds can’t
get over the mountains, so a majority of the water collected from the
coast precipitates out on the windward side of the mountains.
• As the air moves past the mountains, it is now much drier as it
reaches this side (leeward side) because all the water rained out on
the windward side of the mountains. This develops a rain shadow.
Orographic Effect
How is climate formed?
• Where does most energy on Earth come
from?
– The sun: Similar to organisms, climate is
highly dependent on incoming solar energy.
– Energy comes in the form of light, heat, and
other forms of radiation.
What effects climate?
• Greenhouse effect:
– Gases in the atmosphere act like glass in a
greenhouse…
• This traps some of the sun’s heat energy inside the
biosphere as it radiates back out from the Earth.
– How does this effect the atmosphere and
therefore climate?
• Heat energy is trapped inside and warms the
atmosphere.
Greenhouse Effect
What effects climate and
weather?
• Latitude:
– The equator gets nearly constant radiation from the sun.
– At higher latitudes, the light from the sun is not always
the same intensity all year. This also has to do with the
Earth’s axial tilt of 23.5°.
• Distance from the Sun
– Earth is not always the same distance from the sun.
– Different seasons correspond to different distances.
• Seasons relate to weather
Latitude and Earth’s Axis
Monday October 25th
• Learning Target:
– Understand the process of how heat is transferred
through the biosphere and how this effects both weather
and climate.
• Language Objective:
– Describe global climate patterns using terms such as
temperate zone, tropical zone, and polar zone.
What are seasons?
• Why are there seasons? (Hint: What did you find
out in your lab on Friday?)
– Earth is tilted on its axis by 23.5º, which in combination
with unequal heating of the Earth’s surface, leads to
seasons (NOT distance from the sun).
– Axis always pointed towards North Star (Polaris), so
rotation around the sun makes one hemisphere face the
sun and the other hemisphere face away.
• A season is marked by changes in weather and
hours of daylight as a result of this unequal
heating from the sun.
Latitude and Earth’s Axis
• This unequal heating also forms different climate zones.
• What are the three major climate zones?
– Polar: sun strikes at low angle and very little heat energy is
brought in at these areas (66.5° - 90°).
– Temperate: sit between polar and tropic zones; these areas
often have seasons because time of year determines amount of
heat and light energy form the sun (23.5° - 66.5°)
– Tropical: near the equator, so these zones get the most direct
sunlight year-round (0° - 23.5°).
The Seasons
The Seasons
• Why does a temperate zone have more
defined seasons than a tropical (equatorial)
zone?
– Because of Earth’s axial tilt of 23.5°,
temperate zones are more affected by the
changing angle of the sun over the course of a
year.
– Tropical zones receive nearly constant solar
radiation year-round.
Latitude
• Higher latitudes receive less heat energy per unit
area than do regions near the equator.
• How does this effect climate?
– Temperate and polar zones are cooler.
Heat Transport
• How is heat transported in the biosphere?
– By the interaction of the ocean and by the
atmosphere.
• How is it transported by the ocean?
– Through currents.
• How is it transported by the atmosphere?
– Also by currents, although this is often called
wind.
How and Why?
• Hot air or water rises, cool air or water
sinks.
• As hot air or water rises, the colder stuff
rushes in, causing winds in the atmosphere
or ocean currents in the ocean.
• Unequal heating of ocean and air due to
Earth’s axial tilt promotes these hot and
cold masses.
Major Wind Patterns
• Air heats up at the
equator, rises, and moves
to where the cold, dry air
sank (about 30° N and
30° S or 90° N and
90° S ).
• Water at the equator is
also heated and evaporates
into the moving air mass.
• This is why it is so rainy
in the “tropics” --> hot air
rises, cools, and
condenses. Precipitation
then occurs as the moist
air moves across land and
Major Ocean Currents
•Red = warm current
•Blue = cold current
• Wind moves water in the
ocean, producing surface
currents.
• These surface currents are
warm or cool depending
on where they are formed.
• Equator usually has warm
water currents because the
sun is constantly heating
the equator.
• In polar zones, currents
are colder because there is
less sunlight per unit area
throughout the year.
What might effect currents?
• Earth’s rotation
– Get a paper plate
– While your partner rotates the plate (simulating
Earth’s rotation), try to draw a straight line
from the center of the plate to its edge.
• Landmasses (Hint: Orographic Rainfall)
– Wind and water follow the “path of least
resistance” when in motion.