black body radiation

• a perfect black body is an object that absorbs all the radiation that hits it. no radiation is transmitted or reflected
• all objects emit EM radiation due to the energy in their thermal energy stores. this radiation isn't just in the infrared part of the spectrum, it covers a range of wavelengths and frequencies
• the intensity and distribution of the wavelength emitted by an object depends on the object temperature
• as the temperature of an object increases, the intensity of every emitted wavelength increases
• the intensity increases more rapidly for shorter wavelength, causing the peak wavelength to decrease
• during the day, lots of radiation is transferred to the earth from the sun and absorbed, causing an increase in temperature
• at night, less radiation is being absorbed than is being emitted, causing decrease in temperature
• if the atmosphere starts to absorb more radiation without emitting the same amount, the overall temperature will rise until absorption and emission are equal
• as the object gets hotter, peak wavelength decreases. this is because the frequency increases
• hotter objects are blue , cooler objects are red