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Course: NASA > Unit 2
Lesson 4: SpectroscopyInfrared waves (1800)
Created by NASA.
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- Why does the figure at around3:40show Africa much cooler than the other areas even though it is near the equator?(5 votes)
- My guess is rainforests, since South America is cooler in that place too. But I'm not sure.(2 votes)
- Why these three colours are more than others? why?(3 votes)
- How do gamma rays travel at the same speed as radio waves? If gamma rays have a much higher frequency then wouldn't they have to travel a lot further distance compared to radio waves or any other form of EMT? I was under the impression they all traveled at light speed.(2 votes)
- I am not an expert on this, or even moderately good at this. So, don't take this seriously. Might be wrong.
I believe that it's the amplitude you're talking about. Speed is always the same with the light spectrum, but amplitude is what changes. It'd take the same amount of time for a certain peak of gamma rays to reach a point as a peak of visible light. It's not speed, it's height of the waves and the closeness.
Hope this helped. Like I said, I'm not an expert on this, so this might be drastically wrong. If it is, I'm sorry. I did the best I could. Anyway, I hope this helped. And, if no one can get it, you can always Google it. :P(3 votes)
- Why is it that a wall (or hand) can block an infrared signal from a remote control to the TV whereas a radio wave (which has lower energy) can pass through a wall with no problem? I was under the impression that the higher the energy of a wave (ex. x-ray) the more easily it can 'penetrate' stuff...(2 votes)
- From the video, it says that lower-wavelength rays are less absorbed and scattered when going through dense things like galaxies. X-rays cannot go through lead, which is very dense. I assume radio waves can, but I have no idea.(2 votes)
- so is music infrared light?(2 votes)
- No, they're sound waves. :) Sound waves are vibrations, not radiation.(2 votes)
- Is there a scale for nanometers?(2 votes)
- Yes - there are 25,400,000 nanometers in an inch! Your fingernails grow 1 nanometer every day, and a human red blood cell is 6,000-8,000nm across.(1 vote)
- Why is the temperature in infra-red region warmer than that in visible region?
The frequency of visible light is greater than that of infra-red rays. So, the energy of infra red rays will be lesser (E=hv :-Plank's relation) and hence the temperature too.(2 votes) - Infrared waves have a lesser energy than visible light than how does it make atoms shake more which results in heat?(3 votes)
- Infrared light has a longer wavelength on the spectrum of light
so it carries less energy.
Issac Newton who lived from 1643 to 1727 is my closest living
from Lincolnshire. Issac was the first to separate light using a prisum
into various colors. Issac was my smartest ancester.
Did I get the answer right?(0 votes)
- wait so if emitted light has longer wavelngths like infared, then does it have to have high temperature or low temperature... I am a 9th grader and just studied Plank's black body radiation and trying to connect such concepts of infared and the quantum theory on temperature and waves.(1 vote)
- The black body curve in longer wavelengths occurs at lower temperatures. For example, The cosmic microwave background radiates a black body curve in the microwave wavelengths, and it has a temperature of about 3 K.(2 votes)
- 2;12 does our body give off inferred waves?(1 vote)
Video transcript
When you use a remote control to change channels on your TV, your remote is using light waves. But this light is beyond the visible spectrum of light you can see. Back in 1800, William Herschel conducted an experiment measuring the temperature changes between the colors of the spectrum, plus one measurement beyond visible red. When that thermometer registered a temperature warmer than all the other colors, Herschel had discovered another region of the electromagnetic spectrum, infrared light. This region consists of short wavelengths around 760 nanometers to longer wavelengths about 1 million nanometers, or about a thousand micrometers, in length. We can sense some of this infrared energy as heat. Some objects are so hot they also emit visible light, such as a fire. Other objects such as humans, are not as hot and only emit infrared waves. We cannot see these infrared waves with our eyes alone. However instruments that can sense infrared energy, such as night vision goggles or infrared cameras, allow us to 'see' these infrared waves from warm objects like humans and animals. Infrared energy can also reveal objects in the Universe that cannot be seen with optical telescopes. Infrared waves have longer wavelengths than visible light and can pass through dense regions of gas and dust with lower scattering and absorption. When you look up at the constellation Orion, you see only the visible light. But NASA's Spitzer telescope was able to detect nearly 2,300 planet-forming discs in the Orion nebula by sensing the infrared glow of their warm dust. Each disc has the potential to form planets and its own solar system. Incoming ultraviolet, visible, and a limited portion of infrared energy, together sometimes called "shortwave radiation", from the sun drives our Earth system. Some of this radiation is reflected off of clouds and some is absorbed in the atmosphere. Larger aerosol particles in the atmosphere interact with and absorb some of the radiation causing the atmosphere to warm. The heat generated by this absorption is emitted as long-wave infrared radiation, some of which radiates out to space. The solar radiation that does pass through Earth's atmosphere is either reflected off snow, ice or other surfaces or is absorbed by the Earth's surface. This absorption of radiation warms the Earth's surface and this heat is emitted as long-wave radiation into the atmosphere which allows only a small amount to radiate out to space. Greenhouse gases in the atmosphere, such as water vapor and carbon dioxide, absorb most of this emitted long-wave infrared radiation, and this absorption heats the lower atmosphere. In turn, the warmed atmosphere emits long-wave radiation, some of which radiates towards the Earth's surface keeping our planet warm and generally comfortable. The energy entering, energy reflected, energy absorbed, and energy emitted by the Earth system constitutes the components of the Earth Radiation Budget. A budget that's out of balance can cause the temperature of the atmosphere to increase and eventually affect our climate. For scientists to understand climate, they must also determine what drives the changes within the Earth's radiation budget. The CERES instrument aboard NASA's Aqua and Terra satellites can measure the reflected shortwave and emitted long-wave radiation into space accurately enough for scientists to determine the Earth's total radiation budget. Other NASA instruments monitor the changes in other aspects of the Earth's climate system, such as clouds, aerosol particles, or surface reflectivity, and scientists are examining their many interactons with the energy budget. A portion of solar radiation from the Sun that is just beyond the visible spectrum is referred to as near-infrared. Scientists can study how this radiation reflects off the Earth's surface to understand changes in land cover such as growth of cities or changes in vegetation. Our eyes perceive a leaf as green because wavelengths in the green region of the visible light spectrum are reflected while other visible wavelengths are absorbed. Yet, the chlorophyll and the cell structure of the leaf are also reflecting near-infrared light, light we cannot see. This reflected near-infrared radiation can be sensed by satellites, allowing scientists to study vegetation from space. Using these data, scientists can identify some types of trees, can examine the health of forests, and can even monitor the health of vegetation such as forests infested with pine beetles or crops affected by drought. Studying the emission and reflection of infrared waves helps us to understand the Earth's system and its energy budget. Near-infrared data can also help scientists study land cover such as changes in snow, ice, forests, urbanization, and agriculture. Scientists are beginning to unlock the mysteries of cooler objects across the Universe such as planets, cool stars, nebulae, and much more using infrared waves.