Presentation on theme: "* The relative measure of the amount of water vapor in the air * Psychrometer * Water vapor affects the density of the air. * Cold air is heavier than."— Presentation transcript:
* The relative measure of the amount of water vapor in the air * Psychrometer * Water vapor affects the density of the air. * Cold air is heavier than warm air.
* A body of air that has the same temperature and humidity throughout.
* If a large body of air sits over an area of land or water for a long period of time, it will take on the characteristics of the land or water beneath it. * Temperature * Humidity
* Air masses over the equator will have high temperatures. * Air masses over polar regions will have low temperatures. * Air masses over water (maritime) will have high humidity (moisture content). * Air masses over land (continental) will have low humidity (moisture content).
* Air masses tend to form in areas with little wind. * Remember, they sit over an area for a long period of time without moving.
maritime * Air masses that form over water are called maritime. continental * Air masses that form over land are called continental.
* mT * mT – warm, moist air * cT * cT – warm, dry air * mP * mP – cold, moist air * cP * cP – cold, dry air * cA * cA – super cold, dry air
* Warm air rises, and cold air moves in to replace it. * A circulation pattern is formed. * Causes air and water currents to form
Density! * Warm air rises. * Cool air sinks.
How do different air masses form?
* What is a hurricane? * Hurricanes are tropical cyclones. * They form in the southern Atlantic Ocean, Caribbean, Gulf of Mexico, and eastern Pacific Ocean. * Their winds spiral outward in a counterclockwise, circulation pattern.
* What conditions must exist for a hurricane to form? * Low to medium winds blowing in the same direction * 5–30 degrees north of the equator in the ocean * Ocean surface temperature of greater than 80 F that extends down to about 150 feet deep (50 m) * Lower atmosphere must be moist
* How do hurricanes form? * The air mass above the tropical waters takes on the temperature and humidity of the water beneath it. * Incoming winds force the air upward. * The warm, moist air rises, forming water vapor and clouds. * Above the storm, the winds flow outward. * Outside winds blow inward, and the cycle repeats.
* How do hurricanes move? * Hurricanes turn to the right, away from the equator, because of the Coriolis Effect caused by Earth’s rotation. * You will learn about this phenomenon later in the lesson.
* Where does the energy for a hurricane originate? * The Sun heats the oceans. * Warm air rises, and as it cools, it releases energy, fueling the hurricane.
* Why don’t hurricanes form in higher latitudes? * The temperature of the oceans is not warm enough. * The distance is too far from the equator.
* Hurricane Katrina
* Reflective Question How do oceans play a role in the development of weather systems including hurricanes?
* The movement of air in a horizontal direction * What is wind?
* The uneven heating of the Earth causes differences in air pressure. * What causes wind?
* The Sun’s energy is more concentrated at the Equator and spread out more over the poles. * Air over the equator is warm and less dense and has lower pressure. * Air over the poles is cold and denser and has higher pressure. * Why does this happen?
* As warm air at the equator rises, cooler air from the poles will move in and replace it. * Air pressure moves in a pattern from high to low. * Why does this happen?
* As warm air at the equator rises, cooler air from the poles will move in and replace it. * Convection
* The density changes caused by temperature changes create convection cells. * These cause circular patterns of air that circulate over the whole planet. * Global Convection Currents
* Where the convections cells meet, prevailing winds and jet streams form. * They blow from one direction over a certain area of the Earth’s surface. * Global Wind Belts
* Jet Stream
* Forms high in the upper Troposphere between two air masses of different temperatures * Higher temperature difference = faster speed * Due to the Coriolis Effect, it flows around air masses. * Polar Jet: * It dips southward when frigid polar air masses move south. * It tends to stay north in the summer months.
* Jet Stream Animation html
* Named for the direction from which they blow: * Polar Easterlies * Polar Easterlies – High latitudes blow east to west toward the equator * Westerlies * Westerlies – Mid latitudes blow west to east toward the poles * Easterlies (Trade Winds) * Easterlies (Trade Winds) – Low latitudes blow east to west toward the Equator * Prevailing Winds
* Pressure belts form in between the wind belts. * Prevailing Winds
0 o Equator 30 o S 60 o S 90 o S 30 o N 60 o N90 o N MoreDirect Sun Hot
* The winds from the poles blow toward the equator. * The winds from the equator blow toward the poles. * Global Wind Belts
…then why is it defined as the horizontal movement of air? Does the Earth stand still? * If wind is moving north and south, …
* As the Earth rotates counterclockwise, the winds bend and curve around the Earth. * Gustave-Gaspard Coriolis, an engineer and mathematician, described this effect as an inertial force in * The Coriolis Effect
* In the Northern Hemisphere, winds bend to the right of their direction of travel. * In the Southern Hemisphere, winds bend to the left of their direction of travel. * Let’s try a little investigation to see how this works. * The Coriolis Effect
* Weather patterns and systems move in a circular motion due to the bending of the winds caused by the Earth’s rotation. * The Coriolis Effect
* Our Earth is always seeking balance. * In an effort to find balance, there is a continuous cycle of patterns. * What is the driving force behind the changes that create these patterns? * Equilibrium
How are winds produced? * Reflection Question
Ocean Current s
Warm currents flow away from the equator. Cold currents flow toward the equator. * Ocean Currents
* Energy from the Sun heats the water. * Warm water is less dense that cold water. * Warm water rises, and cold water sinks. * As warm water rises, cold water moves it to replace it. * Sun
* Convection Cycle
* Just as wind moves from high pressure to low pressure areas, so does the water. * Winds blow across the surface of the water, causing friction. * The water piles up because the surface currents flow slower than the winds. * Wind
* As water piles up and flows from high pressure to low pressure, gravity will pull down on the water. * This forms vertical columns or mounds of water. * The Coriolis Effect causes the water to curve. * Gravity
* Causes water to move to the right in the Northern Hemisphere * Causes water to move to the left in the Southern Hemisphere * The Coriolis Effect
* Make up 10% of oceans’ water * Up to maximum depth of 400 m * Surface ocean currents are caused by the surface wind patterns. * Surface Currents
Vertical columns or mounds of water at the surface and flow around them Produce enormous circular currents Five major locations: North Pacific - clockwise South Pacific - counterclockwise Indian Ocean - counterclockwise South Atlantic - counterclockwise North Atlantic - clockwise * Gyres
* Oceanic Gyres
* A strong surface current * Begins at the tip of Florida * Flows up the eastern coastline of the U.S. * Crosses the Atlantic Ocean * Causes warmer climate in NW Europe * Gulf Stream
* Surface waters blow to the right of the wind. * As less dense, surface water moves off shore, cold, deep, denser waters come to the surface to replace them. * Upwelling
* The Great Ocean Conveyor: Helps maintain Earth’s Balance
* Make up about 90% of oceans’ water * Differences in density cause them to move. * Differences in density are related to temperature and salinity. * At high latitudes, they sink deep into the ocean basins. * Temperatures are so cold, they cause the density to increase. * Deep Water Currents
* How are ocean currents produced? * Reflective Question
Abnormally high surface ocean temperatures off the coast of South America Causes unusual weather patterns across the globe * El Nino
* Starts because the easterly trade winds weaken and allow the warm waters in the Western Pacific to move east toward South America * This changes where the convection current occurs. * Causing rain where it usually doesn't occur and drought where it usually rain s * El Nino
* El Nino Winter
* El Nino Summer
Abnormally low surface ocean temperatures off the coast of South America Causes unusual weather patterns across the globe * La Nina
* Ocean currents move more slowly than winds. * Oceans hold more heat than the atmosphere and land. * Cold currents will cause nearby coastlines to be cooler. * Warm currents will cause nearby coastlines to be warmer. Where do the cold currents come from? The warm currents? * Ocean’s Effect on Climate
* Predictable Patterns How do these currents affect the climate of the coastline?
* How do our oceans impact climate? * Reflection Questions