Earth's Resources : Atmosphere

Earth's Resources : Atmosphere - Key SQA Definitions

• Natural Greenhouse Effect - The process by which radiation reflected from the Earth’s surface is absorbed by gases in the atmosphere and prevented from escaping into space, thus keeping the Earth warmer than it would otherwise be. 

The Atmosphere

The Atmosphere consists of all of the gases that surrounds the Earth. There is no upper 'edge' to the Atmosphere, the gases just get lower and lower pressure until it becomes the vacuum of space. However, the 'end' of the atmosphere and the 'start' of space is usually defined as about 100km (this is known as the 'Kármán Line'). 

The image below shows a view from the International Space Station. The fading blue colour shows the thinning of the Atmosphere as the height increases:-

There are several layers that form the Earth's atmosphere, each with distinct conditions within:-

The composition of the Earth's atmosphere has changed a lot over the lifetime of the Earth, but it has had roughly the same balance of gases for the last half a billion years:-

The current composition of the Earth's atmosphere is a mixture of mainly nitrogen, with a large proportion of oxygen and then a series of trace elements:-

The Natural Greenhouse Effect 

The atmosphere has an important role in the temperature at the Earth's surface. Without the atmosphere, the temperature  would vary greatly across the day night cycle. As an indication of this, the Moon (without a substantial atmosphere) experiences temperatures of around 127 Celcius facing the Sun and -183 Celcius on the night side. The Earth's atmosphere moderates this incoming heat, reducing the day-side temperatures and increasing the night-side temperatures to levels tolerable to life. 

There is a group of gases that provides an additional warming effect, these are known as 'Greenhouse Gases'. Without this additional warming, known as the 'Natural Greenhouse effect', the heat radiated from the ground would escape quickly into space, and the average surface temperature would be about -20°C. 

The Greenhouse Gases are 

• Carbon dioxide

• Methane

• Nitrous oxide 

• Water Vapour

These gases act 'like a blanket' trapping heat within the Earth's atmosphere:-

Atmospheric circulation & Wind

Due to the fact that the Earth is not flat, the Sun heats different parts of the Earth by different amounts. The areas that receive the most Solar radiation are at the Equator, whereas as the least Solar radiation is received at the Poles:-

Hot air rises at the equator until it reaches the edge of the Troposphere and is forced to move north or south. As it does so, it cools and sinks back downwards. This produces a 'convection cell' and explains the distribution of rainforests and deserts around the globe, due to the uneven distrubtion of warm, moist air. 

There are three such cells between the Equator and the Pole in each hemisphere:-

It is the mass movement of air caused by the convection cells which produces the wind within Earth's Atmosphere. 

The videos below provide a summary of Atmosheric Circulation:-

You would collect numerical information to identify trends and patterns. You’d create models to predict what might happen in the future. You’d explain your findings using graphs, charts, diagrams, tables and infographics. Your work could be used in a number of areas, including  Local and national government, Market research, Business finance and insurance, NHS management, Crime analysis and forensics, Scientific research etc. 

Energy from the Atmosphere : Wind Energy

Wind power uses the energy of moving air to generate Electricity. The diagram below shows a simplified cross-section of a wind turbine:-

When the wind blows, the moving air causes the blades of the wind turbine to rotate. These rotating blades are attached to a shaft which drives a Generator, generating Electricity. 

The energy changes in a Wind Turbine are:-

1. Moving Air (Wind)  - Kinetic Energy.

2. Turbine and generator - Kinetic Energy converted to Electrical Energy.

Wind power generation can only occur in areas which match the following requirements:-

• Steady, strong wind flow that is reliable (as much as wind can be reliable).

• An exposed site with minimal wind disruption.

• Access to populated areas with connection to the National Grid. 

• Water or Land use by other stakeholders can accommodate the Wind power generator.

You would use large machines and vehicles, like diggers and cranes, to get jobs done on construction and demolition sites, roadworks, and in industrial sites like quarries and railways. You could use machines such as Excavators or diggers, Bulldozers, Mobile and crawler cranes, Tower cranes, Piling rigs etc. 

You would carry out daily safety checks on the machine you are using so a basic knowledge of vehicle mechanics would be necesary. You would also change the buckets and other attachments. You might also use forklifts to unload and move materials around the site. If you operated a crane, you would work with a slinger signaler who would attach the loads and direct you by signals or radio.