Transcript Winds
Thermal Energy The energy an object has due to the motion of its molecules. The faster the molecules in an object move, the more thermal energy an object has (thermal energy is temperature). Ocean Currents and Weather Thermal energy carried by ocean currents has a strong influence on climates around the world. Ocean water can hold a lot of thermal energy (warm air holds more than cold) and so temperatures near oceans tend to be more moderate. Gulf Stream and Weather Changes in Weather 1. 2. 3. Changes in weather involve the following: Air movements Formation of Clouds Precipitation Energy is needed to make all of these things happen…where does it come from?! Changes in Weather The Sun!!! Convection is a key player in moving heat throughout the oceans and atmosphere. Convection transfers heat from one place to another. Heat is not distributed equally over Earth. Formation of Wind Wind is the result of the uneven heating of the atmosphere. Air flows from areas of higher pressure to areas of lower pressure, creating wind. Local Winds (Land and Sea Breezes) Ex. An island is surrounded by cold water. During the day, the island heats faster than the water and so the air above the island is warmer. The molecules in the air space out, causing the air to move up and outward. This expansion lowers the air pressure at the island’s surface. Land-Sea Breezes The cooler ocean air moves in toward the low pressure area over the land causes a land-sea breeze. Local vs. Global Winds Local: Influenced by topography Global Winds: large currents of winds that transfer heat from the poles and the equator (just like ocean currents!) Global Winds Travel thousands of miles in steady patterns and last for weeks. Can be categorized into Calm Regions and Wind Belts. Calm Regions 1. 2. Doldrums: Near the equator (low pressure zones) Horse Latitudes: High pressure zones Wind Belts Trade Winds- Two belts of winds that blow from the east. Westerlies- Belts of wind blowing from the west. -All weather in the US travels west to east. Polar Easterlies- Winds that blow from the polar high toward the subpolar low. Pressure Gradient Air flows from high pressure to low pressure. Everything in nature likes to be balanced, thus areas with more pressure move towards areas of less pressure in hopes of being equal/balanced. The lower the pressure, the stronger the wind! Pressure Gradient and Wind The Jet Stream A wind that flows in the upper troposphere from west to east over vast distances at great speeds. Winds in the upper troposphere are very high. The polar jetstream pulls cold air from the pulls towards the equator and the equatorial jetstream pushes warm air from the equator towards the poles. Jet Stream and Travel Airplanes travel at the same height as the jet stream flows (about 6-9 miles above earth’s surface). Airplane travel times can be either lengthened or shortened depending on how strong the winds in a jet stream are. Coriolis Effect The influence of Earth’s rotation on objects that move over Earth’s surface. In the Northern Hemisphere, the winds curve to the right and to the left in the Southern Hemisphere. http://www.classzone.com/books/earth_science/terc/ content/visualizations/es1904/es1904page01.cfm Coriolis and Air Travel Weather Stations 1. 2. 3. 4. 5. Symbols used to determine several factors including: Temperature Cloud Cover Dew Point Pressure Wind Speed (measured in knots/1 knot=1.15 mph) and Direction Reading a Weather Map The center of the symbol represents cloud cover. If it is completely colored in, it means that there is total cloud cover. The lines coming off the cloud cover determine wind speed and direction. These lines are called barbs and point in the direction the wind is coming from.