chap 9 light and lighting l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Chap 9. Light and Lighting PowerPoint Presentation
Download Presentation
Chap 9. Light and Lighting

Loading in 2 Seconds...

play fullscreen
1 / 25

Chap 9. Light and Lighting - PowerPoint PPT Presentation


  • 71 Views
  • Uploaded on

Chap 9. Light and Lighting. Solar Radiation Nature of Solar Radiation Light Quality, Intensity, and Duration Atmospheric Window Greenhouse Effect Light Intensity Measurements Radiometric Method Photometric Method Lighting for Photosynthesis Purpose Light Sources Application

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Chap 9. Light and Lighting' - beryl


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
chap 9 light and lighting

Chap 9. Light and Lighting

Solar Radiation

Nature of Solar Radiation

Light Quality, Intensity, and Duration

Atmospheric Window

Greenhouse Effect

Light Intensity Measurements

Radiometric Method

Photometric Method

Lighting for Photosynthesis

Purpose

Light Sources

Application

Lighting for Photoperiod Control

Purpose

Light Sources

Application

concept of light
Concept of Light

Radiation: A process of emitting energy in the form of electromagnetic waves or particles (photons). It ranges from cosmic rays, gamma rays, x-rays, UV lights, visible light, to infrared and radio waves.

Light: That portion of radiation perceived or the light-restricted portion of spectrum

Irradiation: A process by which a surface is illuminated or irradiated (i.e., irradiation of flower buds with x-ray to induce mutation).

slide3

The Solar Radiation

Visible Light Spectrum

atmospheric windows
Atmospheric Windows

The interaction of electromagnetic radiation with atmosphere allows only light in certain waive length regions to penetrate the atmosphere well. These regions are called atmospheric windows. The filtration of radiation is largely due to CO2, zone, water vapor in the atmosphere.

http://csep10.phys.utk.edu/astr162/lect/light/windows.html

spectral ranges of visible lights
Spectral Ranges of Visible Lights
  • Violet 0.4 - 0.446 µm
  • Blue 0.446 - 0.500 µm
  • Green 0.500 - 0.578 µm
  • Yellow 0.578 - 0.592 µm
  • Orange 0.592 - 0.620 µm
  • Red 0.620 - 0.7 µm
  • Infrared 0.7 - 0.9  µm
light quality
Light Quality
  • What does it mean?

What spectrum of light does it involve? (Red, blue, green, orange, or infrared lights, etc.)

2. Measurements

a. Wave lengths: distance from peak to peak

or valley to valley in units of nm or µm

µm = 10-3 mm

nm = 10-6 mm

Å = 10-3 nm

b. Wave number: number of waves per cm of light (number/cm)

c. Frequency: number of cycles per second (cycles/sec, cps)

Hertz (Hz) = 1 cycle/sec

Mega Hz = 1 million Hz

light intensity
Light Intensity

1. What does it mean?

How much irradiated on the surface (Quantity)

2. Radiometric measurements

a. Light intensity measured in terms of power of radiation on a unit surface area

Power = energy/unit time

Intensity = power/unit area, energy/unit area per unit time

b. Measurement units: Joules cm-2 sec-1, watts cm-2,BTU ft-2 hr-1, kcal cm-2 hr-1

c. The shorter the wave length, the more the energy available.

3. Radiometric measurements

a. Light intensity expressed in terms of illuminance or how bright the light is (visible radiation only)

b. Measurement units: Foot candles, lumens, lux, µmol m-2 sec-1

c. Relationships: 1 lux = 1 lumen m-2

1 foot candle = 10.76 lux

4. Factors affecting light intensity

a. Moisture in the air No. of clear days in January: 70-80% in AZ, 30-40% in NY

b. Topography

c. Pollutants in the air (PAN, SO2, NOx, etc.)

duration of light
Duration of Light

1. What does it mean?

How long the light was on

2. Factors that affect light duration

a. Time of the year (seasonal variation)

b. Latitudes (both northern an southern hemisphere) Fargo: 56.5 N

3. Photoperiod responses

a. Long day plants (short night plants)

Requires days longer than 16 hours to bloom

Aster, petunia, potato

b. Short day plants (long night plants)

Requires days shorter than 13 hours to bloom

Chrysanthemum, poinsettia, kalanchoe

c. Mechanism of responses

Phytochrome system

P660 – red light absorbing form

P730 – far-red light absorbing form

spectral distribution of various lamps
Spectral Distribution of Various Lamps

Spectral Distribution of Various Lamps

Sunlight

Incandescent lamp

Radiant Energy

Fluorescent lamp

Red-Infrared region

PAR region

400 nm

700 nm

high light intensity discharge hid lamps
High Light Intensity Discharge (HID) Lamps

Mercury Vapor Lamp

High Pressure Sodium Lamps

Mercury Lamps

Metal Halide Lamps

influence of photoperiod on poplar tree
Influence of Photoperiod on Poplar Tree

Left - Short Day Grown

Right - Long Day Grown