minimum one page Explaination required...
Write short notes on beam and diffuse radiation.
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Answer:
Flying Turtle logo Energy Photosynthesis Cell Metabolism Applications
Insolation:
Solar Basics:
1. Insolation Intro
2. Definitions
3. Types of Radiation
Insolation Influences
1. Effects of Sun's Angle
2. SA&I data
3. SA&I formula
4. Air Mass
5. AM formula
6. Day Length
7. Clouds and Pollution
Solar Panel Tilt Angles:
1. Tilt Angle
2. Optimal Tilt
3. Load Tilts
4. Tilt Deviation
5. Comparing Tilts-Part 1
6. Comparing Tilts-Part 2
FT Exploring Pages:
1. Home Page
2. Photosynthesis
3. Energy Changes
4. Energy Start Page
5. Types of Energy
6. WIND Energy
7. First Law of Thermo
8. Second Law of Thermo
Direct, Diffuse and Reflected Radiation
This Section: Insolation Definitions Types of Radiation Tilt Angle
Sun Angle and Insolation Air Mass Day Length Clouds and Pollution
This page is one of three introducing insolation-concepts. An overview is at insolation. The other two pages are: insolation definitions and types of radiation.
The solar radiation that fills our sky can be direct, diffuse or reflected radiation.
On this page, we first explain the difference between the two main components of the light in the sky: direct radiation and diffuse radiation.
Second, we talk about what conditions increase the percentage of diffuse radiation in the sky and also about which places tend to have the most direct radiation and which places the least.
A sketch of a man dressed from like the 1800's Europe (knickers, long coat, three-corner hat). He is bending over and looking at his shadow.
"A shadow! Well, that settles it, there is
some direct radiation around here.
Now, if I could just figure out where
it's coming from...."
Third, we explain why tilted solar collectors actually gather a little less diffuse radiation than untilted ones.
Finally, after covering reflected radiation and how much snow can impact it, we conclude with global radiation.
Direct Radiation vs Diffuse Radiation
"Direct radiation" is also sometimes called "beam radiation" or "direct beam radiation". It is used to describe solar radiation traveling on a straight line from the sun down to the surface of the earth.
"Diffuse radiation", on the other hand, describes the sunlight that has been scattered by molecules and particles in the atmosphere but that has still made it down to the surface of the earth.
Direct radiation has a definite direction but diffuse radiation is just going any which way. Because when the radiation is direct, the rays are all travelling in the same direction, an object can block them all at once. This is why shadows are only produced when direct radiation is blocked.
Ratio of direct to diffuse radiation
When the sky is clear and the sun is very high in the sky, direct radiation is around 85% of the total insolation striking the ground and diffuse radiation is about 15%. As the sun goes lower in the sky, the percent of diffuse radiation keeps going up until it reaches 40% when the sun is 10° above the horizon.1
Traffic on a wet, gray day on Wormwood Street in London.
Happy is the Londoner who likes
mostly diffuse radiation!
Atmospheric conditions like clouds and pollution also increase the percentage of diffuse radiation. On an extremely overcast day, pretty much 100% of the solar radiation is diffuse radiation. Generally speaking, the larger the percentage of diffuse radiation, the less the total insolation.
Beam Radiation
Beam Radiation External beam therapy (EBT), also called external radiation therapy, is a method for delivering a beam or several beams of high-energy x-rays to a patient's tumor. Beams are generated outside the patient (usually by a linear accelerator, see below) and are targeted at the tumor site.
Diffused Radiation
Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules or particulates in the atmosphere. Also called sky radiation, diffuse skylight, or just skylight, it is the determinative process for changing the colors of the sky.