3/12/14

Tonight's homework is as follows:

• Work on Assignment 45. See below for assistance.
• Read 20.1 through 20.3 (p. 430 - 434) of Botkin and Keller. This will help you with Assignment 45.
• Review your notes on renewable sources of energy since you will an assessment on Friday.

Students in 12CD, remember that you will be taking the mock AP exam at 1:00pm. Plan accordingly (ie. get the best night's sleep you can, bring a snack, bring a pencil, etc.)

Mr. Whelton's data from today's investigation:

Part 1 (normal air)			Part 2 (CO2 added)
Time (minutes)	CO2 (ppm)	Temp (◦C)	Time (minutes)	CO2 (ppm)	Temp (◦C)
0	646	24.8	0	745	25.1
0.5	636	25.8	0.5	9966	26.5
1	639	26.6	1	9962	28
1.5	680	27.3	1.5	9962	29
2	730	28.2	2	9962	30.1
2.5	789	29	2.5	9962	31.1
3	845	29.9	3	9966	32.1
3.5	892	30.7	3.5	9966	33.1
4	942	31.5	4	9966	33.9
4.5	989	32.3	4.5	9966	34.9
5	1026	33.1	5	9966	35.7
5.5	1042	33.7	5.5	9969	36.6
6	1095	34.4	6	9972	37.4
6.5	1139	35	6.5	9972	38.2
7	1160	35.4	7	9972	38.6
7.5	1173	36	7.5	9972	39.6
8	1195	36.4	8	9972	40.1

Assignment 45 Investigating the Effects of a Greenhouse Gas

Introduction

Global climate change is defined as changes in any aspects of the Earth’s climate, including temperature, precipitation, and storm intensity and patterns. This lab will focus on one of those variables: temperature.

Global average temperature has fluctuated over the past 4.7 billion years. Over the past 900,000 years, the troposphere has experienced prolonged periods of global cooling and global warming. Such periods can be caused by a number of factors:

•       Changes in the length of Earth’s elliptical orbit around the Sun every 100,000 years.

•       Changes in the tilt of the Earth’s axis as it rotates around the Sun every 40,000 years.

•       The wobble of Earth’s axis every 26,000 years.

•       Changes in outputs of energy by the Sun related to 11-year sunspot and 22-year solar magnetic cycles.

•       Large volcanic eruptions.

•       Changes in levels of greenhouse gases in the troposphere.

The greenhouse effect is a natural process that warms the Earth’s lower troposphere and surface because of greenhouse gases. These gases trap heat reradiated from Earth’s surface and are essential to keep the global average temperature high enough to sustain life. Greenhouse gases include water vapor, carbon dioxide, methane, and nitrous oxide. While these gases have been present in the troposphere throughout Earth’s history, their concentrations have significantly increased since the Industrial Revolution. These increases result from burning fossil fuels, clearing and burning forests, and planting rice and using inorganic fertilizers. Global warming is a warming of the Earth’s atmosphere because of increases in the concentration of one or more greenhouse gases.

Today we are going to investigate the effects of carbon dioxide on a surface’s ability to retain heat.

“Investigating the Effects of a Greenhouse Gas” Analysis Questions

Answer all of the following questions to the best of your ability in complete sentences.

1. Thoroughly analyze your data. This means that you should:

·         Graph your data

·         Make inferences and evaluate your hypothesis

·         Support your conclusions by referring to your data

·         Try to explain what happened

2. Monthly mean atmospheric carbon dioxide at Mauna Loa Observatory, Hawaii is graphed below. The carbon dioxide data (red, lighter curve), measured as the mole fraction in dry air^*, on Mauna Loa constitute the longest record of direct measurements of CO₂ in the atmosphere. These records were started by C. David Keeling of the Scripps Institution of Oceanography in 1958 at a facility of the National Oceanic and Atmospheric Administration (NOAA). NOAA started its own CO₂ measurements in May of 1974, and they have run in parallel with those made by Scripps since then. The black (darker) curve represents the seasonally corrected data.

^*Data are reported as a dry mole fraction defined as the number of molecules of carbon dioxide divided by the number of molecules of dry air multiplied by one million (ppm).

Based on the information presented and collected today, what inferences, predictions, etc. can you make? In other words, what are the implications of your observations and conclusions?