Video Transcript
Which type of radiation is trapped
by greenhouse gases in the troposphere? (A) 𝛾, (B) infrared, (C)
ultraviolet, (D) X-ray, (E) radio.
Greenhouse gases are gases found in
the atmosphere both naturally and through human activity. Some examples of greenhouse gases
are carbon dioxide, water vapor, methane, and nitrogen oxides. There are many gases in our
atmosphere, but not all of these gases are greenhouse gases. Greenhouse gases are gases that
contribute towards the greenhouse effect.
When direct sunlight shines through
the glass of a greenhouse, the air inside the greenhouse heats up. The Earth’s temperature increases
in a similar, though slightly more complicated, way. Visible light and ultraviolet, or
UV, radiation from the Sun move through the atmosphere. Some of this radiation is reflected
back into space by the atmosphere and Earth’s surface. And some of the ultraviolet
radiation is absorbed by the ozone layer in the stratosphere. But some of the UV radiation and
visible light is absorbed by the Earth’s surface.
Some of the radiation absorbed by
the Earth is then emitted as infrared, or IR, radiation. Most of this IR radiation is
absorbed by greenhouse gases in the troposphere, the lowest region of the
atmosphere. The energy is then released from
the gas molecules as thermal energy. So the IR radiation remains trapped
in the troposphere and warms the Earth.
From this, we can see that the type
of radiation that is trapped by greenhouse gases in the troposphere is IR radiation,
or infrared radiation, emitted by the Earth, answer choice (B).
