Transcript File
Characteristics of the Atmosphere • https://www.youtube.com/watch?v=dQPyNY2 WIdw&feature=youtu.be • Atmosphere song • https://www.youtube.com/watch?v=OyQlYY5fG8&feature=youtu.be Drops of Atmosphere • The Atmosphere is a mixture of gases that surrounds Earth. It contains the oxygen we need to breathe and protects us from the suns damaging rays. Water in the Atmosphere • Water is found in the atmosphere in three different forms. • Liquid water (water droplets) and Solid water (snow and ice) are found in the clouds. • Most of the water in the atmosphere exists as Water Vapor, which is an invisible gas. Air Pressure and Temperature • Air Pressure is the measure of the force with which air molecules push on a surface. It is higher the closer you get to the Earth’s surface, because there is more air above you. Measured with a barometer. • Air temperature changes depending on the composition of gasses in the area. Layers of the Atmosphere • The Troposphere is the layer closest to the earth. It’s the densest layer, containing almost 90% of the atmosphere’s total mass. This includes almost all of the Earth’s carbon dioxide, water vapor, clouds, air pollution, and weather. • The Stratosphere is the layer above the Troposphere. It contains almost all of the Ozone, which protects the Earth from harmful radiation. The air here is very thin and contains very little moisture. • Above the Stratosphere is the Mesosphere. It is the middle layer and the coldest part of the atmosphere, with temperatures as low as -93 degrees Celsius • The top layer is the Thermosphere. The temperature in the Thermosphere increases with altitude, and can reach all the way up to 1,000 degrees Celsius, but because the particles are so spread out and therefore don’t run into each very much, it doesn’t feel hot. • Beyond the Thermosphere is the Exosphere. This is the uppermost layer of the atmosphere as it gradually fades into the vacuum of space. Air here is very thin. • In the upper Mesosphere and lower Thermosphere, nitrogen and oxygen absorb harmful solar radiation. The gas particles become electrically charged, and are known as ions. This part is called the Ionosphere. Occasionally the Ionosphere radiate energy in the form of shimmering lights known as Auroras. Energy in the Atmosphere • Earth receives energy from the Sun through Radiation, which is the transfer of energy as electromagnetic waves. Even though Earth only receives about 2 billionth of the Radiation the Sun produces, it’s enough to make Earth habitable. • Thermal Conduction is the transfer of thermal energy through a material. It always transfers from warm to cold areas. • Convection is the transfer of thermal energy by the circulation or movement of a liquid or gas. As air becomes heated, it becomes less dense and rises, while cool air sinks. This rising and cooling form a circulatory pattern known as a Convection current. The Greenhouse Effect • The Greenhouse Effect is the process by which gases in the atmosphere absorb thermal energy and radiate it back to Earth. It functions like the roof of a greenhouse by letting solar energy to enter but preventing thermal energy from escaping. This is what keeps the Earth warm. • For the Earth to remain livable, the amount of energy received from the Sun and the amount of energy returned to space must be approximately equal. This is called the radiation balance. • Data shows that the average global temperature has increased in the past 100 years. This is known as Global Warming. • Some scientists have hypothesized that this warming may be caused by an increase in Greenhouse gases in the atmosphere. • Greenhouse gases are gases that absorb thermal energy in the atmosphere. The more Greenhouse gases, the more energy will be trapped on Earth. • Human activity such as burning fossil fuels and deforestation is possibly the cause of the increase.