Both infrared and microwave bands are invisible to the human eye. Then how are IR and microwave images from remote sensing satellites printed? How do they substitute the wavelengths?
Why does sunlight falling on the ground through small holes of any shape appear circular?
turns a purplish-blue colour. The discoloration of the skin could also represent a high level of an abnormal form of haemoglobin in the blood circulating throughout your body. Haemoglobin is the protein responsible for transfer oxygen in your blood.
Cold temperatures can also cause your fingernails to turn blue. That’ s because cold temperatures force your blood vessels to constrict. The narrow pathways make it difficult for the right amount of oxygen-rich blood to get to your nails. If normal nail colour returns upon warming up or massaging your hands, the blue colour was likely due to the that part of your body not getting enough blood supply because of cold temperatures.
Both infrared and microwave bands are invisible to the human eye. Then how are IR and microwave images from remote sensing satellites printed? How do they substitute the wavelengths?
SCIENCE FACTS
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bands and hence can be used as photographic plates for detecting and measuring some of these radiations.
Satellites nowadays use sensors whose working principle is based on photoelectric effect, converting radiation reaching the sensor into electric charge, which can then be easily measured and processed. Essentially, the energy detected over a given spectral band, whether it is in the visible, infrared or microwave band, is converted to an array of digits corresponding to the energy range and radioed to ground stations. After receiving it, those digital values corresponding to the measured energy range( known as grey levels) are finally printed on a computer screen as a picture or as a conventional photograph.
Why does sunlight falling on the ground through small holes of any shape appear circular?
Both infrared and microwaves are part of the electromagnetic spectrum, which stretches from radio waves to gamma rays. Each band of this spectrum corresponds to a small range of frequencies. Each frequency is uniquely connected with an energy level. The total spectrum is very wide. Our eyes respond only to a very small band called the visible band. However, different chemicals do react to certain higher or lower level of energy
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hen light rays travel a long distance they do so in parallel lines. Since the entire density of rays pass through the miniature holes, the shape of the( sun) light corresponds to the shape of the prototype object from where the light emanates. Since the shape of the sun is circular the shape of the sunlight is also circular. Such phenomena are quite common during eclipses. It will be interesting to note that the changes in the shape of the( sun) light falling on the walls or on the ground correspond to the shape of sun / moon, as the eclipse progresses. When the light rays pass through the trees or very small holes( in thatched roofs) the images are circular.
WINSPIRE: Empowering youth | February, 2017