ASTR 1514 1st Edition Lecture 17The Atmosphere of Mars and Climate Change on EarthChapter 7.4-7.5Atmosphere of Mars- The Mass of Mars compared to the Earth is 0.107 Earth mass- Mars has an atmospheric pressure of 0.007 bar, much less than that of Earth’s (1 bar)- The average surface temperature on Mars is -50 C.- Mars has a cold, thin atmosphere so there are extreme temperature variations. - Mars’s axial tilt ranges between 13 degrees and 40 degrees, causing climate instability. - When the axis is tilted the summer pole receives fairly direct sunlight and becomes warm- When the axis tilt is small, the poles receive little sunlight at any time of year. - Boiling point depends on air pressure, On Mars, the air pressure is so low that water spilled on the surface of the planet would immediately evaporate into gas, this process is called sublimation- Mars is farther from the sun than Earth, and it has a much thinner atmosphere, so the daily variation of temperature is large.- Mars’s significant elliptical orbit (0.0934) compared to Earth’s much less elliptical orbit (0.0167) causes Mars to have more extreme seasons. - Mars has a weak magnetic field so solar wind stripping occurs on the planet. - Strong temperature differences between the poles and equator on Mars drive strong global winds that can create global dust storms. Climate Change on EarthClimate Change on EarthWeather: The state of Earth’s atmosphere at a given time and placeClimate: The average state of Earth’s atmosphere, over entire globe. Global Warming and the Greenhouse Effect- The greenhouse effect is very important on Earth; without it the surface would be about 33C colder and the water would be frozen. - Global Warming and Climate Change; Does man’s contribution to global levels of Carbon Dioxide result in global climate change. Carbon Dioxide and Temperature- Historical temperature determined from:1. Paleoclimatology.2. Directly measured from 18503. Indirect methods: tree ring widths, coral growth, and isotope variations4. Two forms of naturally occurring oxygen: 16O and 18O, the lighter isotope evaporates at a lower temperature than the heavier one. 5. So difference in the amount in sediments gives you estimate of temperature. - Historical Carbon Dioxide levels determined from:1. Measuring bubbles of air trapped in Antarctic or Greenland ice sheets.2. Can be correlated to when we know there were ice ages and warm periods. Evidence for Rapid Climate Change- Global sea level change in last 10 years is double of the last 100 years- Global temperature rise- Ocean temperature rise- Shrinking of ice sheets- Declining Arctic Sea Ice- Global Glacial retreat- Record high temperature events are increasing and record low temperature events are decreasing. - Ocean acidification by 30% due to absorption of increasing Carbon Dioxide. *It is hard to predict what will happen as a result of Climate change because weather is a chaoticsystem, small changes in one factor may produce large changes in others. *Normal Conditions- Under normal conditions, trade-winds blow across the Pacific Ocean.- Cold water present along South AmericaEl Nino- Trade winds decrease- Decrease in the upwelling of cold water at South AmericaLa Nina- Trade winds are very strong- A lot of cold is present along South America*The presents of El Nino or La Nina changes the position of the jet stream, shifting where the Pacific moisture is carried into the US. El Nino- El Nino winter is relatively wet and cool over Oklahoma- Last strong El Nino was in 1997, moderate in 2009La Nina- La Nina winter is relatively dry and warm over Oklahoma- Last strong La Nina was in 2010 – the year we started into the recent drought. Some Predictions- Northern regions will become wetter, Southern regions will become drier.- More frequent and intense extreme heat events (heat waves)- More heavy precipitation events- More intense Atlantic Hurricanes - More frequent intense cold-season storms, shifting northward.- Higher Ocean levels- More acidic Ocean, affecting Calcium Carbonate levels, decreasing