What do you picture when you hear the word "equator?" Can there be both extreme heat and extreme cold on the equatorial line?
|
|
What do you picture when you hear the word "equator?" Can there be both extreme heat and extreme cold on the equatorial line?
|
|
David dispels some misconceptions about life at the African equator.
Segment length: 6:00
Run your finger along the equator on a globe. What do you see in your mind's eye
as your finger passes over continents and oceans? Tropical rain forests? Houses
on stilts? Blazing temperatures? Stop your finger on the east African country of
Kenya and be prepared for new impressions. Lying on the equator in the
southwestern corner of Kenya is the Maasai Mara National Reserve - a nature
preserve that defies the usual image of the equatorial tropics.
This reserve is a part of the Serengeti-Mara ecosystem. Here you will find not rain forests, but woodlands and savanna. Two million years ago, volcanic and tectonic activity pushed up the lush forest floors of this region, creating a plateau 1,520 meters (5,000 feet) above sea level. At this elevation, the warm ocean winds were cut off, forests disappeared, and volcanic ash settled over the highlands, creating the rolling plains of today. Temperatures can reach 38oC (100oF) and cool to 10oC (50oF).
Dramatic volcanic action also produced Mount Kenya. Once higher than Mount Everest, Mount Kenya now stands 5,200 meters (17,000 feet) high and is crowned with snow. Snow! On the equator?
Why doesn't the snow melt? First, as one ascends from sea level, the temperature decreases. In fact, according to the adiabatic lapse rate, for every thousand feet, the temperature drops approximately 3.1oC (5.5oF). Second, the shiny surface of the snow reflects the sun's rays, keeping the snow frozen. (This effect is called the albedo.) Third, the snow is so densely packed at the peak that the lower layers of snow cool the surface layer, counteracting the warming effects of the sun.
Life in the shadow of Mount Kenya may defy our equatorial image, too. For a thousand years, the nomadic Maasai have shared their home with wildebeest, lion, and giraffe. More precious to the Maasai are the herds of cattle upon which their livelihood, wealth, and prestige depend. The Maasai villages are built with the materials at hand-mud, cow dung, and sticks. Women are responsible for the construction of the family boma. Life in the manyatta follows traditional patterns, and the roles of its members are clearly defined. Boys take care of the cattle, girls help their mothers, and elders enjoy their honored roles as village leaders. Although life in nearby cities offers modern conveniences, many Maasai prefer the path of their ancestors under the direct rays of the equatorial sun.
Connections
1. Are there other places along the equator that resemble Kenya's geography?
2. What impressions do you have about life on the equator? Are your impressions
facts, generalizations, or misconceptions?
adiabatic lapse rate rate at which the temperature decreases in the troposphere,
or lowest layer of the atmosphere
albedo reflection of the sun's energy off a highly reflective surface
altitude height above Earth's surface or sea level
boma Maasai's mud hut
equator imaginary circle on Earth's surface midway between the north and south
poles
Maasai native tribal people of the Serengeti who maintain their traditional
village life
Maasai Mara National Reserve Kenya's wildlife park on the Serengeti Plains
manyatta Maasai village
savanna plain with grasses and scattered trees, especially near the equator
where the rainfall is seasonal
tectonic activity movement of Earth's upper crust
Main Activity
Explorers of old could determine their location in the Northern Hemisphere by
using a sextant and sighting the North Star. From these, they could calculate
their latitude. Follow these directions to make a simple sextant. Calculate your
latitude to find out how far north you are from the equator.
Materials
1. Draw two lines, each 1.25 cm (1/2") from the edge of the poster board,
so that the lines make a right angle at the corner of the board.
Questions
1. One degree latitude is approximately 110 km (69 miles). How far are you from
the equator?
2. Why is it possible to calculate the latitude by sighting the North Star?
The shiny surface of the snow on Mount Kenya reflects light, keeping the snow
from melting. Try this activity to see why. Take two identical glass jars and
fill them with equal amounts of water at the same temper-ature. Cover one jar
with a piece of foil. Cover the other with a sheet of black paper. Place the jars
outside on a sunny day. After an hour, measure the water temperature of each jar.
Which one is cooler? Why?
Want to find north without a compass? Pound a stick into the ground at an angle
so that it is pointing directly toward the sun and not casting a shadow. Wait
about an hour until the stick casts a shadow about 15 cm (6") long. The
shadow will be pointing east from the stick. Why? Stand with your right shoulder
pointing in the direction of the shadow, and you will be facing north. Now, which
direction is the equator?
The Maasai live in mud huts. What other kinds of houses are built by people
living near the equator? Choose a country and culture to research. Make a model
of a typical house from that area and tell your friends how the architecture and
materials reflect the culture, geography, and resources of the people you
studied.
We encourage duplication for educational
Newton's Apple is a production of KTCA Twin Cities Public Television.
Made possible by a grant from 3M.
Educational materials developed with the National Science Teachers
Association.