Today – 4/27 Radiation Radiation Global Warming Global Warming

XC Opportunity Gallagher Theater, 12:05 – Astrobiology and the Arts If I’m not there, sign in and sit with Randy Richardson

Last Time The three rock types are distinguished by texture and composition Two kinds of sedimentary rocks – clastic and chemical Metamorphic rocks – igneous or sedimentary rocks changed by heat and pressure

Last Time Epicontinental sea Sedimentary (metamorphic) rocks to know: conglomerate (metaconglomerate), sandstone (quartzite), shale (slate, schist), limestone (marble)

The Two Kinds of Radiation Electromagnet (EM) radiation – light in all its forms: gamma rays, X-rays, UV, visible, infrared, microwave, radio Radiation from the decay of radioactive isotopes like U-235. This radiation consists of charged particles (helium nuclei and electrons) and gamma rays

Electromagnetic Radiation EM radiation is a self-sustaining force field that travels through space in the form of waves at the speed of ? The shorter the wavelength of the radiation, the more dangerous it is. So gamma radiation is the worst.

Radioactive Decay Radiation Radioactive decay radiation is bad for you because it consists of energetic charged particles or the worst kind of EM radiation. This is the radiation of the atomic bomb, “radioactive fallout”, and the dirty bomb. The worst damage is done when radioactive isotopes are swallowed or breathed in

Global Warming Speak Insolation – short for “incoming solar radiation”. This is the “energy in”. Albedo – reflectivity. This results in energy out. Higher albedo = more light reflected back into space = more energy out. Snow, ice, and clouds have high albedo, land and oceans have low albedo

Global Warming Speak Greenhouse effect – the atmosphere is transparent to EM radiation in the visible and near-infrared ranges. Some of this light is reflected back into space, but some is absorbed by the Earth’s surface, which re-radiates in the far-infrared range. The atmosphere is NOT transparent to far-infrared radiation because “greenhouse gases” absorb these wavelengths and heat up

Global Warming Speak Greenhouse effect is good! Mean temperature on the moon is -4 °F at the same distance from sun as Earth because no atmosphere = no greenhouse effect! Too much greenhouse effect is bad! Mean temperature on Venus 867 °F because atmosphere is 96.5% CO 2 ! At only ½ the distance from the sun, Mercury’s mean temperature is only 333 °F.

Global Warming Speak Greenhouse gases – water vapor, CO 2, etc. Positive feedback – systemic response to a stimulus that reinforces that stimulus. Think “spiraling out of control”. E.g. temperatures go up, melting high albedo glaciers, revealing low albedo ground, more insolation is absorbed, increasing rate of warming

Global Warming Speak Negative feedback – systemic response to a stimulus that counteracts the stimulus. Think “stabilizing influence”. E.g. temperature goes up, more evaporation, more high albedo clouds reflecting light into space, temperature goes down. This is a dubious example for a number of reasons

(2000)

Middle Cretaceous sea level was approximately 500 feet higher than today! Middle Cretaceous sea level was approximately 500 feet higher than today!