CH 4 til7 notes GEOG 2050

CH 4 til7 notes GEOG 2050 - GEOG 2050-Wintersession...

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Chapter 4 Energy is required when something happens and whenever anything moves Insolation – shortwave electromagnetic energy coming from the sun. Latitude is the key control of how much insolation we receive. At the equator, the amounts of insolation are a little lower than a little north and south of the equator because of cloud cover. Electromagnetic Radiation: o Transmission (25%) – direct passage of solar energy through the atmosphere. o Refraction – refers to a change in direction of the energy and its caused by the light passing through different medians of density. Changes as it moves closer to the earth and it causes light waves to bend Radiation can be refracted as it passes through the atmosphere o Scatter – a change in the direction, but in this case many different directions and it is caused by light bouncing off of dust/gas molecules in the atmosphere. Responsible for the color of the sky Also causes diffused light (direct light) – 20% o Energy transmitted through the atmosphere with no effect. o Reflection – when lights hit the ground and are reflected right back to space. Albedo – proportion of radiation that the object reflects. o 31% - average albedo for the Earth as a whole and a lot of that is due to cloud cover; 31% of the sun that the Earth gets is reflected away. o Absorption - things get absorbed by molecules and get changed into kinetic energy. 45% of the light coming in gets absorbed by the Earth’s surface 24% getting absorbed in the atmosphere The remaining 31% gets reflected back out to space (off of surfaces, clouds) Clouds have 2 different influences of the energy balance and energy budget. o Reflect incoming shortwave radiation o Absorb outgoing longwave radiation to balance the Earth’s energy budget at the surface then they reradiate some of this energy back down to the surface—this is called greenhouse force o When we have relatively high clouds, the greenhouse force dominates. The clouds seem to be thinner and more radiation gets through so you have a net warming effect. o Low clouds are often much thicker, so the reflection of shortwave is much strong and this is a dominant fact that you end up with a net cooling effect. o If you average it out on an annual basis, clouds seem to have a moderating effect - areas that seem to be cloudy in the summertime seem to be cooler and in the wintertime they seem to be warmer; the impact of frequent cloud cover, the temperatures seem to be more moderate. Radiation is only one mechanism for transferring energy. Energy Budget – inputs of energy into the object o Inputs – outputs = +/- change in storage o A negative budget = negative change in storage/decrease in temperature o Key component: Radiation! We can define a radiation energy budget
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CH 4 til7 notes GEOG 2050 - GEOG 2050-Wintersession...

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