DESCRIBING EARTHS ATMOSPHERE CHAPTER 12 LESSON 1 IMPORTANCE

DESCRIBING EARTH’S ATMOSPHERE CHAPTER 12 LESSON 1

IMPORTANCE OF EARTH’S ATMOSPHERE • THE ATMOSPHERE IS A THIN LAYER OF GASES SURROUNDING EARTH. • IT IS HUNDREDS OF KILOMETERS HIGH BUT COMPARED TO EARTH’S SIZE, IT IS VERY THIN. • THE ATMOSPHERE CONTAINS OXYGEN, CARBON DIOXIDE, AND WATER NECESSARY FOR LIFE.

IMPORTANCE OF EARTH’S ATMOSPHERE • EARTH’S ATMOSPHERE ACTS LIKE INSULATION ON A HOUSE. • IT HELPS KEEP TEMPERATURES ON EARTH WITHIN A RANGE IN WHICH LIVING ORGANISMS CAN SURVIVE. • IT HELPS PROTECT US FROM THE SUN’S HARMFUL RAYS.

IMPORTANCE OF EARTH’S ATMOSPHERE • IT PROTECTS EARTH FROM BEING HIT BY METEORS.

ORIGINS OF EARTH’S ATMOSPHERE • MOST SCIENTISTS THINK THAT WHEN EARTH FORMED IT WAS A BALL OF MOLTEN ROCK. • AS EARTH SLOWLY COOLED, ITS SURFACE HARDENED. • ANCIENT EARTH’S ATMOSPHERE WAS THOUGHT TO BE WATER VAPOR WITH A LITTLE CARBON DIOXIDE AND NITROGEN.

ORIGINS OF EARTH’S ATMOSPHERE • WATER VAPOR IS WATER IN ITS GASEOUS FORM. • THE ANCIENT ATMOSPHERE DIDN’T HAVE ENOUGH OXYGEN TO SUPPORT LIFE. AS EARTH COOLED AND ITS ATMOSPHERE COOLED, THE WATER VAPOR CONDENSED INTO LIQUID. • EARTH’S ORGANISMS COULD UNDERGO PHOTOSYNTHESIS, WHICH CHANGED THE ATMOSPHERE.

COMPOSITION OF THE ATMOSPHERE • TODAY’S ATMOSPHERE IS MAINLY MADE UP OF INVISIBLE GASES, INCLUDING NITROGEN, OXYGEN, AND CARBON DIOXIDE. • SOME SOLID AND LIQUID PARTICLES, SUCH AS ASH FROM VOLCANIC ERUPTIONS AND WATER DROPLETS, ARE ALSO PRESENT. • NITROGEN MAKES UP 78% OF THE ATMOSPHERE. 21% OXYGEN

COMPOSITION OF THE ATMOSPHERE • THE SOLID PARTICLES ARE POLLEN, DUST, AND SALT. • THE MOST COMMON LIQUID PARTICLES ARE WATER DROPLETS.

LAYERS OF THE ATMOSPHERE • THE ATMOSPHERIC LAYER CLOSEST TO EARTH IS THE TROPOSPHERE. • THE TEMPERATURE DECREASES IN THIS LAYER AS YOU MOVE AWAY FROM EARTH.

LAYERS OF THE EARTH • THE ATMOSPHERIC LAYER DIRECTLY ABOVE THE TROPOSPHERE IS THE STRATOSPHERE. • THIS LAYER HAS THE GREATEST AMOUNT OF OZONE GAS. • THE AREA OF STRATOSPHERE WITH A HIGH CONCENTRATION OF OZONE IS REFERRED TO AS THE OZONE LAYER.

MESOSPHERE AND THERMOSPHERE • MOST OF THE METEORS BURN UP IN THESE LAYERS INSTEAD OF STRIKING EARTH. • THE IONOSPHERE IS A REGION WITHIN THE MESOSPHERE AND THERMOSPHERE THAT CONTAINS IONS. RADIO WAVES CAN TRAVEL LONG DISTANCES BY BOUNCING OFF EARTH AND THE IONOSPHERE. • AURORAS OCCUR HERE. THEY OCCUR WHEN IONS FROM THE SUN STRIKE AIR MOLECULES, CAUSING THEM TO EMIT VIVID COLORS OF LIGHT.

EXOSPHERE • THE EXOSPHERE IS THE ATMOSPHERIC LAYERS FARTHEST FROM EARTH’S SURFACE. • GRAVITY PULLS THE ATMOSPHERE TOWARDS EARTH. • GRAVITY’S PULL ON AIR INCREASES ITS DENSITY. AT HIGHER ALTITUDES, THE AIR IS LESS DENSE. • COOLER TEMPERATURES IN LOWER LAYERS, WARMER TEMPERATURES OUTSIDE BOTTOM LAYERS.