One of the parents that organized the recent Global Day just shared this with me. I thought it fit to share with you guys since we have been learning about ocean currents this unit. The clockwise flow of the gyre in the north pacific is driving debris from the Japanese tsunami towards our west coast…
I realize that in most biomes and areas in the world when temperature rises precipitation rises as well because the rate of evaporation would rise and cause more rainfall.. but how come in a few areas of the world like we saw in some of the projects a rise in temperatures actually decreases precipitation as shown in figure 4.23 in the book? It doesnt really make sense to me because yes the higher temperatures would rapidly decrease evaporation, but wouldnt it also fall back down at a higher rate in a form of precipitation plus the area in the figure is in California, an area with easy access to a great water mass, the Pacific Ocean.
Note: A guest post by DanaeM from the other class since we have less students.
In class Friday, we talked about the fifth factor that helps determine climate: Ocean currents. These ocean currents are effected by temperature, gravity, prevailing winds, the Coriolis Effect, and the distribution of continents. The resulting phenomena are gyres, upwelling, thermo haline circulation, heat transportation across the globe, and ENSO (El Nino Southern Oscillation.
Gyres:
Gyres are the large scale patterns of water circulation on the surface and these patterns are heavily influenced by prevailing winds. The winds cause the Northern Hemisphere surface currents to rotate in a clockwise direction and the Southern Hemisphere currents to rotate counterclockwise. Areas of different gyres are shown below:
Upwelling:
Upwelling is a vertical mixing that moves cold water upward to the surface. This happens because the wind currents blow the warmer air on the oceans surface away, causing the cold water to have to rise and fill its place. As the cold water moves from the surface, it brings nutrients, like phosphorous and nitrogen, along with it. The picture below serves as a visual:
Thermo Haline Circulation/Heat Transportation across the Globe (these topics are related):
Thermo Haline Circulation is process is driven by salt water because as water warms it expands, and becomes less dense than cold water. By adding salt to the water, the density increases because the salt fills the spaces between the water molecules. And since the hot water is less dense than the cold water, the cold water will sink and flow down the east coast of North and South America. This salinity creates a circulation because the warm water continues to move north and the cold water continues to move south. This current pulls heat north from the equator via ocean currents by the Gulf Stream. As these currents bring the warm water north, they also bringing vast amounts of heat energy to cooler regions, warming areas that other wise would be much cooler.
ENSO (El Nino Southern Oscillation):
As trade winds weaken near South America, it allows for more warm water to move East to the West coast of South America. This transportation of warm water inhibits upwelling which results in a decrease of productivity in the ocean reducing the fish population. Watch the video link posted below for a more detailed/visual description.
Today we talked about climate variety and 4 of 5 factors that determine it.
1. Unequal Heating of the Earth’s Surface
A. The Earth is a sphere so as the angle of the impact of light increases, the amount of energy per meter squared that reaches the surface decreases.
B. The Earth is a sphere so as the angle of the impact of light is closer to 90 degrees (directness), the amount of energy per meter squared increases.
Tucker and Mr. Willard illustrated the temperature difference in the poles, temperate zone, and the equator.
C. As Albedo/Reflectivity increases, the amount of energy absorbed decreases and vice versa.
D. There is an unequal distribution of land and sea. Land and sea have different absorbing properties. Water heats slower and holds heat energy longer while soil heats faster and holds heats energy for a shorter amount of time.
As air heats up, its volume increases and density decreases. Therefore, the air rises. As the air rises it cools so its volume decreases and density increases causing the air to sink. The process of heating and cooling causes winds.
http://teacherdoc.net/6th.Chap10.outline.htm
Here are 2 videos demonstrating the effect.
3. Earth’s Rotation causes the Coriolis Effect.
The Coriolis Effect is the deflection of an object’s path (wind) due to the Earth’s rotation. So the wind is going straight but the earth is turning, which produces “Global Prevailing Winds”.
Coriolis Effect Demonstration on YouTube
Example of the Coriolis Effect in the Northern Hemisphere versus the Southern Hemisphere on Youtube
4. Earth’s tilt and Orbit affects the number of seasons and the type of season.
The Earth is tilted at 23.5 degrees and because of this, as the Earth revolves around the sun, it gets different amounts of energy across its surface. The Northern Hemisphere and the Southern Hemisphere receive different amounts of sunlight during different times of the year due to the tilt of the Earth, and therefore they have different seasons.
Here is a video explaning how the Earth has seasons on Youtube
Also, due to the amount of sunlight different areas of the globe receive throughout the year, the number of seasons that each area has varies.
The poles only have 2 seasons because half of the year the earth is angled so one of the poles is facing almost directly at the sun and the other is facing completely away. During the other half of the year it’s vice versa.
The temprate zones have 4 seasons because they are not as directly in the sun or out of the sun as the poles are.
And finally, the tropics have only one season because they are receiving almost direct sunlight all year long.
Tate and Christina illustrate the rotation and angle of the earth in respect to the sun.
Today in class we learned about the Structure of the Atmosphere. There are 5 layers; (from highest to lowest)Exosphere, Thermosphere, Mesosphere, Stratosphere, and the Troposphere. Today in class we focused on the Stratosphere and the Troposphere. We also discussed the differences between weather and climate.
We narrowed it down to the two layers of the atmosphere, the Stratosphere and the Troposphere. the Stratosphere is the second lowest layer of the atmosphere. The Troposphere extends to 10km(6miles) about earths surface, and the Stratosphere extends from 10km(6miles)-50km(31miles) above the earth’s surface. In the Stratosphere is the Ozone Layer, but not all of the Stratosphere is made up of the ozone layer. The Ozone Layer is able to intercept the sun’s UV rays making it warmer. Without the Stratosphere and the ozone layer there wouldn’t be as much life on Earth. Troposphere is the lowest of all the five layers. All life on Earth is on this level of the earth. The Troposphere is where the air pressure has the highest density. The Troposphere also has more H2O than the other levels in the atmosphere.
The difference between and weather and climate. The weather can change every second of the day. Climate is the average weather of an area over a 30 yr period. Climate is affected by the upper Troposphere and the lower Stratosphere. The weather is affected by the lower Troposphere. In class we discussed about how the climate determines what lives where. There are eight biomes that are all of different climates across the world. Tundra, Taiga, Dessert Grassland, Tropical Rain Forest, Temperate Rain Forest, Temperate Deciduous Forest, and Chaparral.
