Pneumonia can be more severe if you are pregnant. Tell your health care provider if you have signs of pneumonia during pregnancy. If you are pregnant, check with your health care provider before taking any medicine.
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye.Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm.In terms of frequency, this corresponds to a band in the vicinity of 430â770 THz.isible wavelengths pass through the  optical window , the region of the electromagnetic spectrum that allows wavelengths to pass largely unattenuated through the Earth's atmosphere. An example of this phenomenon is that clean air scatters blue light more than red wavelengths, and so the midday sky appears blue.
However, rather than exhibiting a single wavelength, visible light is usually a mixture of wavelengths whose varying composition is a function of the light source from which it is emitted. During day-to-day living, most people encounter only a small number of visible light sources. When venturing outside, for instance, the vast majority of the light that can be seen is emitted from the sun, which also emits many other frequencies of radiation that do not fall in the visible range. Inside, however, visible light primarily comes from artificial sources, most often fluorescent or tungsten devices.