Climate and Geology – Benchmark Review
Climate:
1. Why is the equator typically warmer than the poles?
2. Why is the climate in Washington typically warmer in the summer and colder in the winter?
3. Western Washington generally has warmer winters and cooler summers than Eastern Washington. What physical features are responsible for this difference in climates between Eastern and Western Washington?
4. How are humans affecting the global temperatures?
5. How do you describe climate?
Earth’s Interactions:
- Which geologic process is responsible for causing natural disasters such as (volcanoes, earthquakes, and tsunamis)?
- What is subduction?
- The Juan de Fuca plate is sliding under the North American plate. What feature of Washington was created from this geologic process over millions of years?
- What geologic event happened to cause the weathering and erosion that led to the Columbia River gorge?
Earth’s Historical Climate:
- What is a paleoclimatologist?
- How could a paleoclimatologist find information about past climates?
- What order did these layers and fault line happen in?
- How could a scientist figure out the age of one of the layers in the diagram?
Climate:
1. Why is the equator typically warmer than the poles?
Answer:
On earth, the equator receives more sunshine than do the poles. This is due to simple geometry of the earth's curvature, a given amount of sunshine in a beam falling on the equator, which points directly at the sun, has a much more intense effect than the glancing rays spread over a much larger area of the curving surface near the poles. In addition, extensive ice and snow at the poles reflects back to space some of the sun's energy that reaches the earth. Much more sunshine is absorbed to heat the earth at the equator. This means the land at the equator becomes hotter than the poles. If we had no atmosphere or oceans, the equator would become too hot for life as we know it, and the poles too cold. However, the atmosphere and oceans take some of the excess heat from the equator to the poles, making both habitable to humans. An interesting connection to make is that if the earth were heated evenly at all latitudes there would be no winds or ocean currents.
From: http://education.arm.gov/studyhall/ask/past_question.php?id=694
Climate:
2. Why is the climate in the northern part of Earth typically warmer in the summer and colder in the winter?
Answer:
Because the earth's axis is tilted.
It is all about the tilt of the Earth's axis. Many people believe that the temperature changes because the Earth is closer to the sun in summer and farther from the sun in winter. In fact, the Earth is farthest from the sun in July and is closest to the sun in January!
During the summer, the sun's rays hit the Earth at a steep angle. The light does not spread out as much, thus increasing the amount of energy hitting any given spot. Also, the long daylight hours allow the Earth plenty of time to reach warm temperatures.
During the winter, the sun's rays hit the Earth at a shallow angle. These rays are more spread out, which minimizes the amount of energy that hits any given spot. Also, the long nights and short days prevent the Earth from warming up. Thus, we have winter!
Climate:
3. Why Is Eastern Washington Hotter Than Western Washington in the summer, but colder in the winter?
Answer:
SEATTLE - It was pretty hot over here toward the end of July, but Eastern Washington was baking in triple digits. Why the difference?
Western Washington can thank its proximity to the Pacific Ocean as a natural air conditioning. But the Cascade Mountains act like a wall that keeps the cool air from getting over to the other side, leaving them to bake in the hot summer sun. And even on our hottest days when we get air blowing over from Eastern Washington, the water around here keeps us from getting over 100.
It can work in the opposite way in the winter. Sometimes, arctic air can filter down into Eastern Washington, but it won't be able to jump the Cascades into Western Washington, keeping us in the 30s and 40s while Eastern Washington shivers in the teens and 20s.
Climate:
4. How do you describe climate?
Answer:
Climate is the average weather in a place over many years. While the weather can change in just a few hours, climate takes hundreds, thousands, even millions of years to change.
Sometimes the climate of a place is described with graphs like this. This graph shows
how temperature usually changes over a year for a particular place on Earth.
Climate:
5. How are humans affecting the global temperatures?
Answer:
How do we know that humans are the major cause of global warming?
The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) states: it is a greater than a 90 percent certainty that emissions of heat-trapping gases from human activities have caused “most of the observed increase in globally averaged temperatures since the mid-20th century.” We all know that warming—and cooling—has happened in the past, and long before humans were around. Many factors (called “climate drivers”) can influence Earth’s climate—such as changes in the sun’s intensity and volcanic eruptions, as well as heat-trapping gases in the atmosphere.
So how do scientists know that today’s warming is primarily caused by humans putting too much carbon in the atmosphere when we burn coal, oil, and gas or cut down forests?
· There are human fingerprints on carbon overload. When humans burn coal, oil and gas (fossil fuels) to generate electricity or drive our cars, carbon dioxide is released into the atmosphere, where it traps heat. A carbon molecule that comes from fossil fuels and deforestation is “lighter” than the combined signal of those from other sources. As scientists measure the “weight” of carbon in the atmosphere over time they see a clear increase in the lighter molecules from fossil fuel and deforestation sources that correspond closely to the known trend in emissions.
Earth’s Interactions:
1. Which geologic process or plate boundary is responsible for causing natural disasters such as (volcanoes, earthquakes, and tsunamis)?
Answer:
Look up the answer to this question in your notes or read through the handout about different types of tectonic plate boundaries.
Earth’s Interactions:
2. What is subduction?
Answer:
Subduction is the process of the oceanic lithosphere colliding with and descending beneath the continental lithosphere.
Earth’s Interactions:
3. The Juan de Fuca plate is sliding under the North American plate. What feature of Washington was created from this geologic process over millions of years?
Answer:
Pacific Mountain System - Cascades volcanoes
Ring of Fire
The Cascades volcanoes define the Pacific Northwest section of the ‘Ring of Fire’, a fiery array of volcanoes that rim the Pacific Ocean. As if volcanic hazards were not enough, the Ring of Fire is also infamous for its frequent earthquakes. In order to understand the origins of this concentrated band of Earth hazards we have to take a peek beneath our feet.
If we could slice deep into the Earth from the Pacific Ocean through the Pacific Northwest, we might see something like the image below. Beneath the Cascades, a dense oceanic plate plunges beneath the North American Plate; a process known as subduction. As the oceanic slab sinks deep into the Earth's interior beneath the continental plate, high temperatures and pressures allow water molecules locked in the minerals of solid rock to escape. The water vapor rises into the pliable mantle above the subducting plate, causing some of the mantle to melt. This newly formed magma rises toward the Earth's surface to erupt, forming a chain of volcanoes (the Cascade Range) above the subduction zone.
Earth’s Interactions:
4. What geologic event happened to cause the weathering and erosion that led to the Columbia River gorge?
Answer:
The Missoula Floods
16,000-14,000 years ago (Pleistocene)
Did you know that the largest floods to occur on the planet happened here? During the last ice age, ice sheets covered much of Canada. One lobe of ice grew southward, blocking the Clark Fork Valley in Idaho. This 2,000 foot (600 meters) high ice dam blocked the river, creating a lake that stretched for hundreds of miles. When the lake was full, it contained 600 cubic miles (2,500 cubic kilometers) of water. How much is that? Imagine a block of water a mile high (as high as the mountains around Bonneville Dam), a miles wide, and stretching from Bonneville Dam to San Francisco!
Eventually, water traveled under the ice dam. The water drained out of the lake in two or three days, flooding eastern Washington. The flood, moving up to sixty miles per hour, scoured out hundreds of miles of canyons called coulees, created the largest waterfall to ever exist, and left 300 foot (90 meter) high gravel bars. At Bonneville, the water crested at 650 feet (200 meters). If you look on the cliffs southeast of the dam, you will see a transmission tower (the one with three poles) that is 200 feet (60 meters) above the high water mark.
During a period of 2,500 years as many as 100 of these floods scoured the Gorge.
Earth’s Historical Climate:
1. What order did these layers and fault line happen in?
Answer:
Superposition: The most basic concept used in relative dating is the law of superposition. Simply stated, each bed in a sequence of sedimentary rocks (or layered volcanic rocks) is younger than the bed below it and older than the bed above it. This law follows two basic assumptions: (1) the beds were originally deposited near horizontal, and (2) the beds were not overturned after their deposition.
Earth’s Historical Climate:
2. How could a scientist figure out the age of one of the layers in the diagram?
Answer:
Relative Dating
Faunal Succession: Similar to the law of superposition is the law of faunal succession, which states that groups of fossil animals and plants occur throughout the geologic record in a distinct and identifiable order. Following this law, sedimentary rocks can be "dated" by their characteristic fossil content. Particularly useful are index fossils, geographically widespread fossils that evolved rapidly through time.
Earth’s Historical Climate:
3. What is a paleoclimatologist?
4. How could a paleoclimatologist find information about past climates?
Answer:
Paleoclimatology is the study of past climates. Since it is not possible to go back in time to see what climates were like, scientists use imprints created during past climate, known as proxies, to interpret paleoclimate. Microbial life, such as diatoms, forams, and coral serve as useful climate proxies. Other proxies include ice cores, tree rings, and sediment cores (which include diatoms, foraminifera, microbiota, pollen, and charcoal within the sediment and the sediment itself).
Past climate can be reconstructed using a combination of different types of proxy records. These records can then be integrated with observations of Earth's modern climate and placed into a computer model to infer past as well as predict future climate.