Britain Is On Red Alert! What Happened?

The Parliament building in the picture is actually emitting electromagnetic radiation, and it is this radiation that is being captured by the camera.

Everything in the universe that has a temperature above absolute zero emits electromagnetic radiation. This may surprise you, as if you turn off the lights in your room you don’t see the furniture glowing. We don’t see the glow because our eyes have evolved to be sensitive to only a small range of frequencies of electromagnetic radiation, visible light, and objects don’t usually emit a lot of radiation in those frequencies unless they are very hot. In other words, we often casually say that the wood in fires glows when it gets hot. That’s not really true, however. The wood is glowing all the time, and our inability to measure it is the fault of our eyes, not that the wood all of a sudden starts glowing.

The intensity of electromagnetic radiation emitted by an object at some temperature as a function of the frequency of the radiation is known as the blackbody spectrum. The spectrum peaks, which means that the intensity is highest, for a particular frequency that depends solely on the temperature of the object and a combination of physical constants. The higher the temperature, the higher the peak frequency. We see this in a fire as well. If you look at the embers of a fire, they glow, and as the embers cool down their color becomes redder and redder, i.e. the peak frequency of their emission drops.

By pointing a camera that is sensitive to a range of frequencies below those of visible light we can see the emission at many different frequencies from a cool object. If the camera can measure the amount of light hitting it at different frequencies it can determine what the peak frequency is and so determine the temperature of the object. This temperature is then translated via software to a false color image such as that displayed on the screen.

As a final fun fact, when I said everything glows, I meant everything. Even the whole universe glows with a spectrum corresponding to a blackbody at about 2.7 Kelvin. This residual background radiation tells us a tremendous amount about the evolution of the whole universe.

If you are interested in Electromagnetic Radiation, you can look at Behold the power of the sun!

The right side of the photograph has a temperature thingy, things that have heat emit electromagnetic radiation at different wavelengths depending on their heat energy

Infrared (IR) light is electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum. and this type of thermal camera observe infrared rays only!!!

Its simple. All you have to pay attention to is the scale at the right. 10 c being the hottest would definitely be the building with lights and fans and electricity flowing. The sky on the other hand must be colder assuming its night time. Electromagnetic radiation is the only solution that fits.

It cant be light because if it were we would be seeing a normal image. All things radiate electromagnetic(in this case, heat) waves and each object radiates a different wavelength and that can be attributed to the different colors we see in the image.

As we know the hotter body emits more IR Radiation than cooler bodies. So in the image the cooler sky is in blue color emits less IR radiation and the building being hot emits more radiation is in yellow and red color.

The scale beside the image we see constitutes the scale of visible electromagnetic spectrum, i.e., electromagnetic radiations between 400 and 750 nm. The photograph here is made using electromagnetic radiation from sunlight and I think this image is used to study the fall or increase in daily temperature....I am not sure though.