GLOBAL WINDS
BACKGROUND
TRADE WINDS POWERED TRANSCONTINENTAL COMMERCE FOR CENTURIES. IN ADDITION, THE TRADE WINDS ARE THE MOST
CONSPICUOUS AND STEADY WIND SYSTEM ON EARTH. CONDITIONS THAT CAPTAINS OF SAILING VESSELS WANTED TO STEER CLEAR
INCLUDED AVOIDING BEING CAPTURES BY PIRATES, SCURVY, AND SAILING INTO THE INTER TROPICAL CONVERGENCE ZONE (THE
DOLDRUMS). IN THE ITCZ A SHIP WOULD BE STUCK SAILS FLAPPING WITH NO MEANS OF RESUPPLY.
CAPTAINS DID NAVIGATE IN THE TRADE WIND ZONES. THE TRADE WINDS WERE NAMED BY SAILORS ON TRADING VESSELS. IN THE
NORTHERN HEMISPHERE THE TRADE WINDS BLOW FROM THE NORTHEAST TO THE SOUTHWEST SO SHIPS COULD CONSISTENTLY SAIL
QUICKLY TO THE WEST. SOUTH OF THE EQUATOR THE WINDS BLOW FROM THE SOUTHEAST TOWARD THE NORTHWEST SO SHIPS
COULD DEPENDABLY RETURN HOME.
WIND IS MOVEMENT OF AIR AS A RESULT OF TEMPERATURE DIFFERENCES OR PRESSURE DIFFERENCES CAUSED BY UNEQUAL
HEATING OF THE ATMOSPHERE. THE SURFACE OF THE EARTH IS CURVED, AS A RESULT, ENERGY FROM THE SUN IS ABSORBED BOTH
DIRECTLY AND INDIRECTLY.
AREAS NEAR THE EQUATOR RECEIVE DIRECT (CONCENTRATED) ENERGY SO THEY ARE WARM. AREAS NEAR THE POLES RECEIVE
INDIRECT (DIFFUSE) ENERGY SO THEY ARE COLD. AIR OVER LAND HEATS UP AND COOLS DOWN FASTER THAN AIR OVER WATER.
WHEN THE EARTH WARMS, IT WARMS THE AIR AND WHEN THE EARTH COOLS, THE AIR COOLS. THE WARM LESS DENSE AIR RISES AND
THE COLD DENSE AIR MOVES IN AND REPLACES THE RISING WARM AIR. WINDS MOVE FROM AREAS OF HIGH PRESSURE TO AREAS OF
LOW PRESSURE.
WINDS ARE NAMED ACCORDING TO THE DIRECTION FROM WHICH THEY BLOW. GLOBAL WINDS BLOW FROM SPECIFIC DIRECTIONS AND
COVER LONG DISTANCES.
ANSWER QUESTIONS
1. DESCRIBE WIND.
7. WHAT DOES THE WARM AIR FROM THE EQUATOR DO?
2. DESCRIBE AIR PRESSURE.
8. WHY ARE THE POLES COLD?
3. DESCRIBE AIR.
9. WHAT DOES THE COLD AIR FROM THE POLES DO?
4. HOW ARE WINDS ARE NAMED?
10. DESCRIBE CORIOLIS FORCE.
5. DESCRIBE GLOBAL WIND.
11. DESCRIBE WIND VANE.
6. WHY IS THE EQUATOR WARM?
12. DESCRIBE ANEMOMETER.
1. LABEL THE DIAGRAM WITH THE TERMS:
HORSE LATITUDES, POLAR EASTERLIES, PREVAILING WESTERLIES, TRADE WINDS, INTER TROPICAL CONVERGENCE ZONE
2. COLOR THE WIND BANDS:
HORSE LATITUDES = RED
POLAR EASTERLIES = BLUE
PREVAILING WESTERLIES = PURPLE
TRADE WINDS = GREEN
INTER TROPICAL CONVERGENCE ZONE = BROWN
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