Lesson 1:

What is the Atmosphere

What you should know by the end of this lesson:

The composition (makeup) of the Atmosphere
Brief understanding about each layer of the Atmosphere

What is the Atmosphere?

Originally formed as the earth cooled, the atmosphere is a blanket of gases that contains solid material, such as volcanic dust and blown soils, and is attached to the earth by the force of gravity.

The atmosphere is a mixture of oxygen (21%), nitrogen (78%), argon (0.93%), carbon dioxide (0.037%), and other gases such as hydrogen, helium, neon, krypton, xenon, and ozone. It also contains water vapour which varies from 0-4%.

These gases are densest at the Earth's surface and get less dense with increasing height. Around 90% of the atmosphere by weight lies in the lowest 15 km (9 miles) above the surface and it is only a very thin skin of air that keeps all life on Earth alive.

The composition or make-up of the atmosphere does vary from place to place and at different times of year. However, the 4 main gasses tend to remain fairly stable throughout the atmosphere.

Digital Workbook and Paper Jotter

Sketch a quick copy of the table below
Choose appropriate colours and shade it in to show the composition of the 4 main gasses (you will need to add a box for Carbon Dioxide)
Don't forget the key!

Layers of the Atmosphere?

Lesson 1 Worksheet

There are 5 Layers of the Atmosphere. Each has distinct characteristics and features which make it stand out from those around it.

Digital Workbook Task (Or if you are able to print off worksheets):

Print off or Copy the Layers of the Atmosphere worksheet into your digital workbook (OneNote)
Add descriptions of the features at each layer.

Paper Jotter Task (and no access to a printer):

Draw a quick sketch of the Earth with 5 levels above it - (best to start at the top of your page and work down to ensure you have enoug room)
Add descriptions of the features of each layer.

Exosphere

The upper limit of our atmosphere is the exosphere. The main gases within the exosphere are the lightest gases, mainly hydrogen, with some helium, carbon dioxide, and atomic oxygen. Satellites orbit the exosphere.

Thermosphere

The thermosphere is directly above the mesosphere. The thermosphere, named from the Greek (thermos) for heat, begins about 80 km above the earth and can experience temperatures of 2,500°C (due to an increase in atomic oxygen, which absorbs incoming radiation).

Mesosphere

Many rock fragments from space burn up in the mesosphere (50-90km up). As it lies between the maximum altitude for aircraft and the minimum altitude for orbital spacecraft, this is the most poorly understood part of the atmosphere. Temperatures fall rapidly with an increase in height as there is no water vapour, clouds, dust, or ozone to absorb the incoming radiation. It also has the strongest winds (3000kmph).

Stratosphere

The stratosphere (16-50km up) is dry with rising temperatures. No weather occurs in the stratosphere. The stratosphere contains over 15% of the total mass of the atmosphere. It contains large amounts of ozone gas which protects life on earth by filtering out most of the Sun’s harmful rays.

Troposphere

The troposphere contains approximately 75% of the atmosphere's mass and has an average depth of about 16 km. The troposphere is where weather systems develop.

Lapse Rate: The temperature decreases by 6.4°C for every 1000m in altitude.

Temperature Change

Temperature Lapse

As the atmosphere is partly controlled by gravity, it gets “thinner” further away from the earth. This means that the molecules of a gas are further away from each other. This is why people get altitude sickness when they are up high mountains - their bodies are struggling to get enough molecules of oxygen.

The temperature of the atmosphere also changes.

Describe this graph, using numbers in your answer and referring to both pressure and temperature.