Previously, we had assumed a simplified model of Earth; one in which our planet had not atmosphere. This allowed us to examine the basic effects of albedo, latitude, and seasons on our planet's overall average temperature. We'll now add the atmosphere into our figuring; this will complicate matters, but will also make our model more realistic.
Before radiation used for remote sensing reaches the Earth's surface it has to travel through some distance of the Earth's atmosphere. Particles and gases in the atmosphere can affect the incoming light and radiation. These effects are caused by the mechanisms of scattering and absorption.
Objects in the universe send out an enormous range of electromagnetic radiation. Scientists call this range the electromagnetic spectrumwhich they have divided into a number of categories. The spectrum is shown in Figure 1, with some information about the waves in each part or band.
When I use the term lightyou are used to thinking of the light emitted by a bulb that you can sense with your eyes, which we now know consists of many wavelengths colors of light from red to blue. As I mentioned briefly before, radio waves are also light waves. Infrared radiation is a kind of light wave usually abbreviated as IR. The same is true of ultraviolet waves UVx-rays, and gamma-rays.
Leia Mais. Leia esta entrevista com a Domi The electromagnetic spectrum is the range of frequencies the spectrum of electromagnetic radiation and their respective wavelengths and photon energies.
All the stars, including the sun, emit radiation. Terrestrial sources, such as a nuclear reactor or an atom bomb, also produce radiant energy. This radiation travels through space in a straight line till it is reflected, deflected or absorbed when it encounters some other entity.
Electromagnetic waves have a vast range of practical everyday applications that includes such diverse uses as communication by cell phone and radio broadcasting, WiFi, cooking, vision, medical imaging, and treating cancer. In this module, we discuss how electromagnetic waves are classified into categories such as radio, infrared, ultraviolet, and so on. We also summarize some of the main applications for each range.
Gamma-rays are the most energetic form of light and are produced by the hottest regions of the universe. They are also produced by such violent events as supernova explosions or the destruction of atoms, and by less dramatic events, such as the decay of radioactive material in space. Things like supernova explosions the way massive stars dieneutron stars and pulsars, and black holes are all sources of celestial gamma-rays. A gamma ray is a packet of electromagnetic energy--a photon.
Gamma-rays Gamma-rays have the smallest wavelengths and the most energy of any other wave in the electromagnetic spectrum. These waves are generated by radioactive atoms and in nuclear explosions. Gamma-rays can kill living cells, a fact which medicine uses to its advantage, using gamma-rays to kill cancerous cells.
Different frequencies of EM radiation have different degrees of penetration. For example, if we take the human body as the object, visible light is reflected off the surface of the human body, ultra-violet light from sunlight damages the skin, but X-rays are able to penetrate the skin and bone and allow for pictures of the inside of the human body to be taken. If we compare the energy of visible light to the energy of X-rays, we find that X-rays have a much higher frequency.