Plates, Climate and Weather
The Changing World
How did the world get to look like it does today?
250 Million years ago some believe that all of the continental plates were linked together in what is called Pangaea which is Greek for "all earth".
- 150 million years ago Pangaea begin to split apart
- "continental drift" theory
- Term was coined by Alfred Wegener
- Now referred to as "plate tectonics"
3 Types of Plate Boundaries
- The earth's crust is made up of about 30 plates that float above the molten interior of the planet. Lighter, thicker areas of the plates form continents. Denser, thinner areas form the ocean floors
- Plates slide along, bump into and move away from each other.
- Earthquakes and volcanos are common near boundaries between plates.
Transform Plate Boundaries
These Plates move side-by-side -- sometimes in opposite directions, sometimes in the same direction. This type of plate movement can cause earthquakes.
Convergent Plate Boundaries
When one plate moves under another plate- subduction- earthquakes and volcanos can occur, In the long run, the subducted plate will disappear. Convergent plates can be found near South America and the coasts of Asia, and in the western Pacific.
Divergent Plate Boundaries
These plates move away from each other in opposite directions. The Mid- Atlantic range is on a divergent plate boundary. the movement causes the Atlantic Ocean to widen about 1.5 miles every 100,000 years.
Weather
Weather is the condition of the atmosphere at a given time and place. Weather involves temperature, precipitation, humidity, wind and other factors.
- Temperature- is the measure of how hot or cold the air is near the earth's surface.
- Precipitation- includes, rain, snow, sleet, and hail. Although on average, 10 inches of snow equals about 1 inch of rain, the actual ratio varies. Dry powdery snow equals less rain than wet, heavy snow.
- Humidity-is the amount of water vapor in the air, affecting the level of comfort and chance clouds will form.
- Seasonal winds- affect weather patterns by moving warm, cold, moist, or dry air to a region.
Climate
While weather describes an area's atmosphere at a specific time, climate describes the usual weather pattern of a region over a period of time. Elevation, latitude, distance from oceans, and surface currents help determine a region's climate.
- Temperature and moisture decrease with elevation
- Latitude affects temperature. Regions within the Tropics of Cancer and Capricorn receive direct sunlight and are warmer than polar areas within the Arctic and Antarctic Circles
- Earth's rotation and coasts of the continent drive most surface currents in a circular pattern, transferring warm ocean water near the Equator to higher northern and southern latitudes.