Transcript Life on an Ocean Planet

Choose to view chapter section with a click on the section heading.
►The Solar Connection
►The Coriolis Effect
Chapter Topic Menu
►The Winds
Exit
 Life gets almost all its energy from the sun. Solar energy
does more than provide energy for life on Earth; it drives
the wind and it drives the currents in the ocean. Earth’s
temperature relies on sunlight. Therefore, the sun not only
provides life, but also the conditions in which life exists.
Air and Sun
Chapter 8 Pages 8-3 to 8-5
The Solar Connection


Air is a mixture of gases that surround us.
The four layers of the atmosphere include:
 1. Troposphere – the lowest layer. This
one concerns us most.
 2. Stratosphere
 3. Mesosphere
 4. Thermosphere – the top layer which
goes out into space.
8-2
Menu
Previous
Next
Air and Sun (continued)
 The amount of water vapor in the air
relates to air temperature, density,
and pressure.
 When a saturated or nearly saturated air mass cools, it has more water vapor in
it than it can hold. The vapor condenses, forming rain when the temperature
is above freezing or snow when temperature is below freezing.
Chapter 8 Pages 8-6 & 8-7
The Solar Connection
 As temperature rises, air pressure
increases, and density decreases.
 Adding water vapor decreases the
density even more.
 Warm air is less dense than cool air.
 Understanding air masses and the weather they create is important because:
 1. These movements redistribute heat around the Earth.
 2. Precipitation is the primary source of fresh water.
8-3
Menu
Previous
Next
The Earth’s Heat Balance



About 50% of all the sunlight that reaches the
atmosphere makes it to Earth’s surface.
To maintain balance with the heat from the sun, all
the energy absorbed reradiates through various
paths back into space as infrared radiation.
If this process were imbalanced with more heat
coming in than leaving, the Earth would grow
hotter and hotter until life perished.

Factors that cause the Earth to heat unevenly:

Chapter 8 Pages 8-8 to 8-14
The Solar Connection
Uneven Heating

The Earth is round, the Earth’s axis is tilted, and the
Earth’s orbit is elliptical hence the distance between
the Earth and sun varies with time of year.
Uneven heating causes weather – in part due to convection.

Convection is vertical circular currents caused by temperature differences in a fluid
such as air. Warm air becomes less dense and rises. Cool dense air comes in to replace
it, which in turn warms and rises. This creates a circular airflow pattern.
8-4
Menu
Previous
Next
Deflection to the Right or Left
 The Coriolis effect is the tendency for the path of a moving object to deflect to
the right in the Northern Hemisphere and to deflect to the left in the
Southern Hemisphere.
The Earth’s Rotation
Chapter 8 Pages 8-15 to 8-19
The Coriolis Effect
 The Coriolis effect is caused by the Earth’s
rotation relative to an object in motion
over its surface.
 Motion or lack of motion is relative to the place
from which you observe it.
 Standing on the equator relative to anyone on the Earth, you’re motionless.
 Someone at a fixed point in space would say you’re moving. To that person, you are
moving because the Earth is rotating.
 Major Ocean Gyres: The Coriolis effect creates circular airflow and current
patterns such as the major ocean gyres – in the Northern Hemisphere to the
right and in the Southern Hemisphere to the left.
8-5
Menu
Previous
Next
The Coriolis Effect and the Wind
Chapter 8 Pages 8-20 & 8-21
The Winds
 The Coriolis effect deflects the air to the right in the Northern Hemisphere. This
gives the air a circular flow pattern rather than a straight north-south pattern.
 Atmospheric circulation cells are six distinct air masses (three in each
hemisphere) with individual air flow patterns.
 Of the six cells, the most important are the Hadley cells.
These lie between the equator and approximately
30° north or south latitude.
 Trade winds are caused by air rising at the equator
and moving northward. The air becomes dense
enough from cooling and moisture loss to sink. Most
of the air descends and flows back toward the
equator, deflecting westward as it flows.
 Between 30° and 60° latitude are the Ferrel cells. They
exist because some of the wind that descends from
the Hadley cells doesn’t turn toward the equator.
Instead it continues on toward the poles shifting to the right (Northern Hemisphere) as
it moves. This is what causes the Westerlies, getting this name because they’re from
the west.
8-6
Menu
Previous
Next
Chapter 8 Pages 8-22 & 8-23
The Winds
Intertropical Convergence Zones (ITCZ)
 The geographic equator is 0° latitude.
 The meteorological (ITCZ) equator is an
imaginary line marking the temperature
equilibrium between the hemispheres that shifts
north and south of the geographic equator with
seasonal changes.
 The ITCZ equator is important because
atmospheric and ocean circulation are
approximately symmetrical on either side of
it – not at the geographic equator.
 The Earth’s major deserts are found at 30°
latitude. Here the downward vertical
airflow brings dry air to the Earth’s surface.
This leads to areas with little rainfall and
significant evaporation.
 Where oceans/seas are alongside deserts, the combination of high evaporation
and low rainfall makes the salinity of these waters higher than average.
8-7
Menu
Previous
Next
Monsoons and Cyclones


Chapter 8 Pages 8-23 to 8-25
The Winds

Monsoons are seasonal wind pattern changes caused by heating or cooling on the
continents. Monsoons cause summers with significant rainfall and winters with very little.
Cyclones are large rotating storm systems of low pressure
air with converging winds at the center. There are two main
types: extratropical and tropical.
 Extratropical cyclones occur where the Polar and Ferrel
cells meet.
 Tropical cyclones form within a single atmospheric cell.
In both cases, cyclones form when moist wind gets drawn
into a low-pressure area, causing it to twist around on itself.
 Cyclones appear to rotate the “wrong” way with respect
to the Coriolis effect.
 When a cyclone forms, the low pressure pulling the wind
into the pattern is stronger than the Coriolis effect.
 The winds that get drawn in and provide the cyclone energy are pulled away from the
Coriolis effect. This imparts the “backwards” spin.
 Cyclones help with the redistribution of heat that is important to all life on Earth.
8-8
Menu
Previous
Next