AECC II: EVS: Unit 1- Basics of Environment

What are the various gases that comprise the atmosphere? Which of the gases is the most predominant?

Answer explanation

The atmosphere is normally composed of 79% nitrogen, 20% oxygen and 1% as a mixture of carbon dioxide, water vapor, and trace amounts of several other gases such as neon, helium, methane, krypton, hydrogen, and xenon.

Which layer of the atmosphere is concerned with the sustenance of life forms?

• Thermosphere

• Troposphere

• Mesosphere

• Biosphere

Answer explanation

The layer we call home: Closest to the surface of Earth, we have the troposphere. "Tropos" means change. This layer gets its name from the weather that is constantly changing and mixing up the gases in this part of our atmosphere.

The troposphere is between 8-17 km thick depending on where you are on Earth. It's thinnest at the North and South Pole.

This layer has the air we breathe and the clouds in the sky. The air is densest in this lowest layer. In fact, the troposphere contains three-quarters of the mass of the entire atmosphere. The air here is 78% nitrogen and 21% oxygen. The last 1% is made of argon, water vapor, and carbon dioxide.

https://spaceplace.nasa.gov/troposphere/en/

Which layer of the atmosphere do planes fly in?

• Troposphere

• Stratosphere

• Mesosphere

• Thermosphere

Answer explanation

The Stratosphere is the second layer of the Atmosphere. It extends from 17 Km to around 48 km of the earth's surface. Airplanes fly in this layer because it does not have clouds and hence causes less turbulence while flying.

One very important feature of the stratosphere is that it contains the _____ layer.

Answer explanation

The presence of ozone in the stratosphere prevents about 99% of the sun's harmful ultraviolet (UV) radiation from reaching the earth's surface, thereby protecting humans from cancer and from damage to the immune system.

Which of the following atmospheric layers is the coldest?

• Stratosphere

• Ionosphere

• Mesosphere

• Exosphere?

Answer explanation

Mesosphere

·         The Mesosphere is found above the stratosphere.

·         It is the coldest of the atmospheric layers.

·         The mesosphere starts at 50 km above the surface of Earth and goes up to 80 km.

·         The temperature drops with altitude in this layer.

·         By 80 km it reaches -100 degrees Celsius.

·         Meteors burn up in this layer.

·         The upper limit is called Mesopause which separates Mesosphere and Thermosphere.

Auroras occur in the ____________

Answer explanation

Thermosphere

·         This layer is found above Mesopause from 80 to 400 km.

·         Radio waves that are transmitted from the earth are reflected by this layer.

·         The temperature starts increasing again with increasing height in this layer.

·         Aurora and satellites occur in this layer.

The layer of the atmosphere where ionization occurs is called the __________

Answer explanation

Ionosphere

·         The lower Thermosphere is called the Ionosphere.

·         The ionosphere consists of electrically charged particles known as ions.

·         This layer is defined as the layer of the atmosphere of Earth that is ionized by cosmic and solar radiation.

·         It is positioned between 80 and 400 km above the Mesopause.

Which of these is the outermost layer of the atmosphere?

• Stratosphere

• Ionosphere

• Exosphere

• Thermosphere

Answer explanation

Exosphere

·         It is the outermost layer of the atmosphere.

·         The zone where molecules and atoms escape into space is mentioned as the exosphere.

·         It extends from the top of the thermosphere up to 10,000 km.

Which part of Earth's structure does the lithosphere comprise?

• The upper core and lower mantle

• The mantle

• The crust and upper mantle

• The inner and outer core

Answer explanation

The lithosphere is the solid, outer part of Earth. The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth’s structure. It is bounded by the atmosphere above and the asthenosphere (another part of the upper mantle) below.

https://education.nationalgeographic.org/resource/lithosphere

The two types of lithosphere are _______ lithosphere and ___________ lithosphere.

Answer explanation

Oceanic lithosphere is associated with oceanic crust, and is slightly denser than continental lithosphere.