|The rays from the Sun supply most of the heat on the Earth's
surface. Some places receive more heat than other places. Some places
receive so little heat from the Sun that ice covers them the entire
|Due to the curved surface of the Earth, some places receive
more direct Sunrays than others. The direct Sunrays focus heat
on an area. Less heat occurs where the rays are less direct. The
drawing to the right shows how the more direct rays occur near
the Equator. Direct rays are also called vertical rays. The term
vertical describes rays that are coming from directly overhead.
Because the Earth is round, not all of the Sun's rays strike the
Earth in a vertical, or direct, manner. These less direct rays
are called oblique rays. Oblique rays are spread out when they
strike the Earth, and because of this they lose some of their
heat. The picture shows that the arrows representing oblique
rays are farther apart as they reach the North and South Pole.
||The Polar Axis is shown at a 23-degree inclination. What
other Earth line is shown at 23 degrees from level?
||Which pole is receiving the most Sun's rays? North ______ or
||The Sun's rays strike the Earth more obliquely at A ______
or B ______
On your globe find the location where the International Date Line (180
E/W) and the Equator intersect. Find the numbers marking the degrees of
latitude north and south from the Equator. On the west side of the
International Date Line, write the percent of heat received at every 10,
north and south from the Equator to the North Pole.
|Equator, 0 degrees
|10 degrees latitude
|20 degrees latitude
|30 degrees latitude
|40 degrees latitude
|50 degrees latitude
|60 degrees latitude
|70 degrees latitude
|80 degrees latitude
|90 degrees latitude
||The purpose of the table to the left is to show the amount
of the Sun's heat measured at various degrees of latitude. The
table assumes that the Equator is receiving 100% of the Sun's
The tables show that the Sun's rays create more heat in the
low latitude zones and less heat in the high latitude zones.
10 latitude shows more heat than the amount at the Equator
due to drier air at this latitude. Dry air and fewer clouds
allow more Sun's rays to reach the Earth's surface at this
90 latitude is the location of the pole. This area received
just a little more than one-third (1/3) of the heat that occurs
at the Equator.
Hot or Cold?
Use the globe and the research you have already done to answer these
||Arrange these places in order from the warmest to the
coolest. Place 1 in front of the warmest location. Place 2 in
front of the location that is warmer than the others but cooler
than one. Complete this ranking until you put the number 8 by
the coolest location.
|_____ Tokyo, Japan
||_____ Portland, Oregon
|_____ Lagos, Nigeria
||_____ Point Barrow, Alaska
|_____ Helsinki, Finland
||_____ Mexico City, Mexico
|_____ Pretoria, South Africa
|_____ Dublin, Ireland
||Which of the following has the coolest temperatures?
||_____ Low latitudes _____ Middle latitudes _____High