Infrared Waves and the Sun

Infrared radiation refers to the kind of electro magnetic radiation that has a longer wavelength than visible light. However, infrared radiation has a wavelength shorter than that of radio waves. The name infrared has a connection with the moniker, VIBGYOR. Since red light has the longest wavelength among the visible lights in the spectrum, the term infrared which means "below red" is used to refer to the kind of light which can be felt but not seen. Infrared spans three orders of magnitude and its wavelength ranges from 750nm to 1mn. One of the major sources of infrared is the sun. The sun is the biggest emitter of infrared radiation. The energy that is emitted from the sun sustains all life processes on Earth. It also maitains the Earth's climate and its weather.

Infrared radiation is popularly known as "heat" or "heat radiation" as people associate all radiated heat to infrared radiation. However, this is an incorrect assumption . Even visible light carries heat along with it. The infrared light that the sun emits only accounts for 50% of Earth's heat. The rest of it is produced by the visible rays which due to their longer wavelengths are absorbed and re-radiated better. Infrared radiation emits heat. However, unlike heat that is transmitted through the process of thermal conduction, infrared radiation can pass heat even in a vacuum. One of the most important concepts in the understanding of infrared radiation is the concept of emissivity. To put it in different words, in infrared radiation, if two objects have different emissivities, they will not not appear to have the same temperature although their physical temperature in visible light may be identical.

The ways in which infrared radiation can be used are varied. From night vision equipments to infrared photography to even infrared heating devices, infrared today is being put to use in various different ways. The infrared night vision equipments are used for seeing in the dark. Such instruments were specifically used by the armies during the Second World War. Digital cameras use infrared filters to capture images. Camera phones and some of the low end digital cameras see infrared light as a white light. Infrared is also used in remote controls. The reason behind this is that one of the biggest use of infrared is its ability to transmit heat without it touching the surface. Infrared is also used in heating devices. Nowadays, devices like infrared sauna that utilize its heating properties have been devised. Infrared is also used in communication. IR data transfer is now one of the fastest ways of communicating.

The sun is the major emitter of infrared rays owing to this fact that around 50% of heat that our earth recieves can be directly attributed to the infrared emissions that we recieve from the sun. Another specific feature of this radiation is that much of it is not visible to the naked eye. The infrared light from the sun may cause minor burns on human skin if they are exposed to it for a substantial duration. At times it can lead to slight redness or minor pain and even a little bit of damage to the epidermis. Often it is advised that when you go out in the sun for longer durations, you must cover the exposed parts of your body with a broad spectrum sunscreen to avoid any possible damage from it. Usage of lotions or creams that contain titanium dioxide or zinc oxide is preferred as they reflect infrared rays falling on the skin. These oxides are known for pulling down the heating affect of the infrared rays. Again, some compounds that use ultra micronised variations of iron oxide can protect the skin by scattering infrared waves.