Getting Energy to the Biosphere Science 10 PDF

THE BIOSPHERE Science 10 WEATHER & CLIMATE Weather refers to the conditions of temperature, air pressure, cloud cover, precipitation, and humidity that occur at a particular place at a particular time. E.g., Today the weather is sunny, but tomorrow the weather may be overcast. Climate is the aver...

THE BIOSPHERE Science 10 WEATHER & CLIMATE Weather refers to the conditions of temperature, air pressure, cloud cover, precipitation, and humidity that occur at a particular place at a particular time. E.g., Today the weather is sunny, but tomorrow the weather may be overcast. Climate is the average weather conditions that occur in a region over a long period of time; usually a minimum of 30 years. E.g., On average the weather is Calgary is much warmer than Northern Alberta. THE EARTH Earth’s biosphere is a relatively thin layer of Earth that is suitable for supporting life. The biosphere is made of three interacting components: 1. Atmosphere - The layer of gases surrounding the Earth 2. Lithosphere - The solid portion of Earth, composed of rocks, minerals and elements 3. Hydrosphere - All the water on Earth, whether present as liquid, vapour, or ice 1. ATMOSPHERE The atmosphere rises 500 km from the surface of the Earth. It is mainly composed of a mixture of gases (air). Nitrogen, the most abundant gas, is required for plant growth. Gas Percent of Oxygen is required for life and key to many Atmosphere by Volume (%) chemical reactions. Nitrogen (N) 78.08 Water vapour exists in the atmosphere, Oxygen (O) 20.95 but at variable levels. Other Gases* 0.97 * Includes argon, carbon dioxide, neon, helium, methane and krypton. 2. LITHOSPHERE Sun The lithosphere is the solid portion of the biosphere. The lithosphere extends from the surface to a depth of about 100km. Deeper than this is the upper mantle which is partially molten. The lithosphere is found on land and under the worlds oceans. The lithosphere is warmed by: 1. Incoming energy from the Sun e Mantl 2. The molten materials of the mantle. 3. HYDROSPHERE The hydrosphere is all the water on the planet. Approximately 97% of this water is salt water in the oceans and seas. The remaining 3% is fresh water. However, this represents all lakes, rivers, aquifers, water vapor in the atmosphere, and glacial snow and ice. Like the lithosphere, the hydrosphere is also mostly warmed by the Sun, but also by the molten materials of the mantle. BIOSPHERE INTERACTIONS The components of the biosphere interact with each other. They all share boundaries and overlap. Water vapor in the atmosphere is part of the hydrosphere. Soil, a part of the lithosphere, also contains water. Water is required for life - some of the most productive aquatic habitats are the margins where the hydrosphere and lithosphere come together. As for the atmosphere, all plants and animals exchange gases to and from the atmosphere regardless if they on land or in water. SOLAR ENERGY Virtually all of the energy on Earth initially comes from the Sun, or from solar energy. Some of this energy is stored as chemical energy by plants. Most is converted in thermal energy. Thermal energy is the energy possessed by a substance by virtue of the kinetic energy of its molecules of atoms. Different areas of Earth receive different amounts of solar energy. What causes this relationship and what consequences does it have for the biosphere? RADIANT ENERGY Solar energy is radiant energy, or energy that is transmitted as electromagnetic waves. Solar energy consists of electromagnetic waves at different wavelengths, which make up the electromagnetic spectrum. The electromagnetic spectrum can be divided into classes of waves that fall within a certain wavelength. Energy per wave also varies across Visible light, the light that humans can see with the spectrum. our eyes, makes up only a tiny portion of the Gamma rays carry more energy EMS. than an equal number of radio waves. INSOLATION Not all regions of the Earth receive the same amount of energy from the Sun. In general, regions at, or near, the equator receive more solar energy than regions nearer to the poles. Insolation refers to the amount of solar energy received by a region on Earth’s surface. Insolation depends on: 1. Latitude – imaginary lines that run parallel to Earth’s equator; the equator has a latitude of 0°, the north pole has a latitude of 90° N. 2. The specific characteristics of the lithosphere, atmosphere and hydrosphere in a region. ANGLE OF INCLINATION If we line up Earth’s poles relative to the plane of its orbit around the Sun, we see that its slightly tilted. Angle of inclination – the degree by which Earth’s poles are tilted from the perpendicular of the plane of its orbit. Earth has an angle of inclination of 23.5°. This has consequences for the amount of solar energy that strikes Earth’s surface. EARTH’S ORBIT AND ANGLE OF INCLINATION Earth orbits the Sun once per year. On the first day of summer (June 21) the angle of inclination causes the North Pole to be tilted towards the Sun. This means the North Pole receives more insolation during the summer. At the same time, the South Pole is tilted away from the Season Simulator Sun, receiving less insolation and therefore cooler temperatures. LATITUDES Earth can be divided into different latitudes, which are imaginary lines that run parallel to the equator (0°) At more northern latitudes, there are more hours of daylight as the North Pole becomes tilted towards the Sun. A solstice is one of two points in Earth’s orbit at which the poles are most tilted towards or away from the Sun. Summer solstice (June 21-22) = most hours of daylight in the year. Winter solstice (December 21-22) = fewest hours of daylight in the year. Regions of Earth nearer to the equator experience less variation in the hours of sunlight they receive year round. INSOLATION AND THE ANGLE OF INCIDENCE The shape of Earth also affects the insolation of regions of different latitudes. Angle of incidence is the angle between a ray falling on a surface and the line of the perpendicular to that surface. At the equator, the angle of incidence of incoming solar radiation is 0°. The larger the angle of incidence, the same amount of solar radiation is spread over a larger distance. Therefore areas of higher latitude receive less solar energy per square km than that of lower latitudes. ABSORPTION & REFLECTION Once solar radiation reaches the Earth one of two things will happen: 1. Reflection – when particles reflect energy they change its direction. 🢝 Reflected energy goes back into space or is absorbed elsewhere in the biosphere. 2. Absorption – when particles absorb energy its is converted into another form of energy, typically thermal energy. 🢝 When a substance absorbs energy, the temperature of that substance will increase. ALBEDO The solar radiation that does reach Earth’s surface is either reflected or absorbed. The amount that is reflected or absorbed depends on the type of surface the radiation encounters. The albedo of a surface is the percent of solar radiation it reflects. Light-coloured, shiny surfaces have high albedo (e.g., snow) Darker, dull surfaces have low albedo (e.g., forests and soil) One contributing factor to climate change is the melting of polar ice, which historically has reflected large amounts of solar radiation. NATURAL GREENHOUSE EFFECT Natural greenhouse effect is the absorption of thermal energy by Earth’s atmosphere. Without this natural process, the average temperature on Earth’s surface would be 33°C lower and most likely be unable to support life. Greenhouse gases – gases that contribute to the greenhouse effect (mainly H2O, but also CO2, N2O, CH4, etc.) by absorbing thermal energy. NET RADIATION BUDGET Much of the solar radiation is reflected out into space or re-emitted as thermal energy. Earth’s net radiation budget is the difference between the amount of incoming radiation and of outgoing radiation re-emitted from Earth’s surface and atmosphere. Incoming radiation is all the solar energy that reaches Earth’s surface – it does not include the radiation reflected by at atmosphere or surface albedo. Net radiation budget = incoming radiation – outgoing radiation Outgoing radiation is the thermal radiation re-emitted by the atmosphere and Earth’s surface that is not absorbed by greenhouse gases.