Astronomy FINAL ch 8: Earth's atmosphere

what does the greenhouse effect do

incoming sunlight heats planet, infrared radiation leaves and cools it, gases like CO₂ and water delay this radiation from leaving earth, warms by 59^oF

what would happen without the greenhouse effect

all of earth’s water would be frozen solid, temp would be -0.4^oF

two of the most effective greenhouse gases

carbon dioxide and water, contained through water cycle and in rocks and water

how does the greenhouse effect work on venus

makes it warmer by over 400^oK, does not contain carbon dioxide

earth’s primary atmosphere

mostly hydrogen and helium, escaped due to low mass and escape velocity for gases as well as high temperatures

earth’s secondary atmosphere

formed 1 billion years after molten crust hardened, was originally CO₂

secondary atmosphere’s sources

volcanoes (carbon dioxide, ammonia, sulfur dioxide, methane, and argon) and comet impacts

the most abundant molecule in the atmosphere

nitrogen because liquid water absorbs CO₂

what creates the ozone layer

life evolving in the oceans 2.5 billion years ago and emitting oxygen

troposphere

surface to 10-15 km, temperature and pressure decline with altitude, water vapor is here and weather occurs

stratosphere

15-50 km, temperature rises with altitude, ozone absorbs light and heats it

mesosphere

50-90 km, no ozone, temperature declines with altitude, upper part is coldest of whole atmosphere

ionosphere (thermosphere)

90 km and up, UV radiation and solar winds ionize atoms which heat it up, solar wind flow of particles from the sun which are electrons, protons (hydrogen nuclei), and helium

why is the sky blue

mostly nitrogen molecules in the atmosphere bend and scatter blue light more than red because of the sun

why is sunset red orange and yellow

blue light is scattered and absorbed when light travels the longest day

increase in abundance of carbon dioxide leads to

stronger greenhouse effect, which leads to global warming

consequence of warmer average temperatures

more heat, which is stored in the oceans and powers extreme weather events