e.s 3.2

Many people consider ozone proaction an international environmental success story. Scientists continue working to protect the ozone layer because CFC molecules remain active in the stratosphere for ___ years

60-120

are clouds that form at altitudes of about 21,000 m during the arctic and antarctic winter or early spiring, when air temperatures drop below -80ºC

Polar stratospheric clouds

The destruction of ozone causes a thin spot, or ____, which lasts for several months

ozone hole

UV light can damage plants by interfering with ___

photosynthesis

High levels of UV light can kill _____ that live near the surface of the ocean

phytoplankton

strong circulating winds over Antartica, called the _____, isolate cold air from surrounding warmer air

polar vertex

At the earth's surface, CFCs are chemically ___. They do not combine with other chemicals or break down into other substances.

stable

But CFC molecules break apart high in the ____ where UV radiation is absorbed

stratosphere

By shielding earth's surface from most of the sun's UV light, the ozone in the stratosphere acts like a ____ for earth's people

sunscreen

is a thinning of stratospheric ozone that occurs over the pole during the spring

the ozone hole

is the layer of the atmosphere at an altitude of 15 to 40km in which ozone absorbs ultraviolet solar radiation. Ozone is a molecule made of three oxygen atoms.

the ozone layer

When sunlight returns to the South Pole in the spring, molecular chlorine is split into___ chlorine atoms by UV radiation. The chlorine atoms rapidly destroy the ___.

two;ozone

are hydrocarbons in which some or all of the hydrogen atoms are replaced by chlorine and fluorine -they destroy ozone molecules

Chlorofluorocarbons

a group of nations made an agreement, called the _____, to sharply limit their production of CFS

Montreal Protocol

____ is harmful to organisms because it can damage the ____ material in living cells

UV light;genetic

UV light is_____ to living things because it damages ____, the genetic material that contains the information that determines inherited characteristics

dangerous;DNA

As the amount of ozone in the stratosphere ____, more UV light is able to pass through the atmosphere and reach Earth's surface

decreases