Exam # 1 Study Guide The following questions/statements are meant to help you focus on the most important concepts thatwe’ve covered so far in class (and in the textbook). They do not represent all possible questions that could be asked on the exam.Exam 1 covers Week 1 – Week4 Lectures (chapters 1 – 3 in the textbook)1. What are the 2 most abundant elements in the universe?- Hydrogen and Helium 2. What are the 4 main steps in solar system formation?- Clouds of gas and “dust” exist throughout our galaxy and the universe- Some event triggers the collapse of the cloudo (Increase in density and driven by gravity by… Passing star Supernova Collision Density Waves Magnetic Field  Others- As the cloud collapses it flattens and spins faster o During the collapse The cloud rotation rate increases, due to conservation of angular momentum. The cloud heats up, as compressing the gas cause the particles to speed up, increasing the temperature of the gas and dust particles. The disk of gas and dust flattens, as collisions between the particles of the cloud loosing energy in the direction perpendicular to the cloud’s rotation. - Strong stellar winds associated with young stars, and/or photo evaporation helped clear remaining gas from between the planets 3. Know the orbital parameters that determine how sunlight is distributed on the planets.- Distance from the Suno The size of the surface area of light is related to its distance from the source. The larger the area over which light is spread, the smaller the amount of energy that passes through any unit area of that sphere.- Orbital Eccentricity (1 st Milankovitch Theory)o The Earth’s orbit is an ellipse o Eccentricity: measure of the departure from circularity o The shape of the Earth’s orbit changes during a cycle that spans about 100,000 years changing from circular to elliptical and then back again METR 1014 1st Edition- Axial Tilt (2 nd Milankovitch Theory)o The inclination of the planet’s axis in relation to its plane of orbit around the Sun.o Ex. Oscillation in the degree of Earth’s axial tilt occur on a periodicity of 41,000 years from 21.5° to 24.5°. - Direction of Tilt in Spaceo The amount of heat energy received at any location of the globe is related to the angle at which the sunlight strikes the Earth (varies by location, time of day, and season) due to the Earth’s orbit around the Sun and the Earth’s rotation around its tilted axis4. Scientists estimate our solar system is approximately how old?- 4.6 billion years old5. What are the two primary reasons that the inner planets (Mercury, Venus, Earth, and Mars) are rocky and smaller than the outer planets (Jupiter, Saturn, Uranus and Neptune)?- The nebula heats up during the collapse. The densest, hottest part of the nebula is at the center. As a result of this, all material very near the protosun existed in a gaseous state. As you move outward, the nebula is cooler. At different radii, the temperature is low enough for certain materials to condense.- The composition of the original cloud was primarily H and He; other, heavier elements madeup a relatively small percentage of the cloud. The inner portion of the nebula, nearest the forming star, was hot, allowing condensation of primarily metals and rocky materials- In the outer regions of the forming solar system, more volatile materials (e.g. ices) were ableto condense. The cores of the outer planets were able to grow large enough to trigger runaway growth, thus accumulating significant amounts of H and He6. What is the most abundant gas in the atmospheres of Venus and Mars?- CO2 and N27. Where did Earth’s atmosphere and oceans come from?- As earth warmed and partially melted, water locked in the minerals as hydrogen and oxygen was released and carried to the surface by volcanic venting activity - Although the released vapor condensed into clouds in the atmosphere and provided precipitation, earth's surface was so hot that rain simply boiled off again and reformed into water vapor --but as this process continued, earth's surface began to cool - As earth surface cooled, the rains eventually formed oceans - Simple bacteria thrived on sunlight and CO2 - a simple form of bacteria developed that could live on energy from the Sun and carbon dioxide in the water, producing oxygen as a waste product.- Once life formed (around 3.5 to 3 billion years ago) and primitive cyanobacteria flourished,levels of O2 would start to rise.- Meanwhile, the ammonia molecules in the atmosphere were broken apart by sunlight, leaving nitrogen and hydrogen. The hydrogen, being the lightest element, rose to the top of the atmosphere and much of it eventually drifted off into space.- The atmosphere upon which life depends was created by life itself.8. Know the percentage of air pressure at different altitude relative to the sea level pressure.- At sea level pressure is at 1000 mb, but as altitude increases, every 5.5 km the pressure is decreased by half. o Example- at 5.5km above sea level the pressure is down to 500 mb9. What was the most likely composition of Earth’s early atmosphere?- 4.6 billion years ago – most likely hydrogen (H2) and helium (He)- Probably rich in hydrogen compounds like methane (CH4), ammonia (NH3), hydrogen cyanide (HCN), water (H2O), and formaldehyde (HCHO). Also some N2, CO2, but LITTLEor NO free oxygen- Molecules of H2 and He move really fast, especially when warm, that they eventually all escaped Earth’s gravity and drifted off into space. - The heat that is still trapped inside Earth from its formation is what leads to volcanic formation10. What is the primary source of energy for Earth’s atmosphere?- The sun11. What are the 4 interacting “spheres” (components) of the Earth System? Know their boundaries and their unique features.- Atmosphere: thin layer of gas or air that surrounds the earth. Processes in the atmosphere include winds, weather, and the exchange of gases with living organisms. - Hydrosphere: water and ice on or near the surface of the Earth. Includes, water vapor in clouds; ice caps and glaciers; and water in the oceans, rivers, lakes, and aquifers. Processes in the hydrosphere include the flow of rivers, evaporation, and rain.- Geosphere: physical elements of the Earth’s surface, crust, and interior. Processes in the geosphere include continental drift, volcanic eruptions, and earthquakes.- Biosphere: the wealth and diversity