Climatic Interactions

Our Atmosphere is a mixture of nitrogen, oxygen and other gases Our Atmosphere is a mixture of nitrogen, oxygen and other gases. It has several layers, but the weather we experience occurs in the bottom layer, known as the troposphere.

Three ways of heat transfer to Earth: 1. Radiation 1. Solar Radiation is energy in the form of heat directly from the sun a. Used to drive winds and natural cycles b. The equator gets the most direct rays

Three ways of heat transfer to Earth: Conduction Heat energy is transmitted through direct contact between neighboring molecules.

Three ways of heat transfer to Earth: 2. Convection 1. Transfer of heat by actual motion of a fluid…a liquid or gas in the form of currents. a. Responsible for global weather patterns b. Main cause of global convection is uneven heating of the Earth by the sun c. Convection occurs when warm, less dense fluids rise and cooler, more dense fluids sink.

1. Hot air is less dense than Cool Air vs. Hot Air 1. Hot air is less dense than cold air so it rises Cold air is more dense than warm air so it sinks. All this motion causes winds to form and transfers heat from the equator to the poles and vice versa.

Humidity is the relative measure of the amount of water vapor in the air. Water vapor affects the density of the air. Cold air is more dense than warm air. A Psychrometer is a device that measures the amount of moisture in the air.

Sea breeze – cool air moves from water to land as warm air rises in daytime Land breeze– cool air moves from land to water as warm air rises at nighttime

Energy Transfer and Weather A. Air Pressure 1. Cool air will hold less moisture a. Molecules move closer together causing air to become more dense and to sink b. HIGH atmospheric pressure areas form here; weather is typically dry and free of clouds cover. 2. Warm Air will hold more moisture a. Molecules move further apart causing the air to become less dense and to rise b. LOW atmospheric pressure areas form here; weather is usually rainy

B. Air Masses A large body of air that has the same properties as the originated area. a. Maritime (m) is an air mass that develops over an ocean; moist. b. Continental (c) is an air mass that develops over land areas; dry.

C. Fronts A boundary forms where a cold air mass and warm air mass meet 1. Warm front develops when a warm air mass meets a cold air mass. Less dense warm air slides up & over the cold air. 2. Cold front develops when a cold air mass invades a arm air mass forcing warm air rapidly up.

What causes wind? *The uneven heating of the Earth causes differences in temperature and densities. (Pressure) WHY? 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

Anemometer or Windmeter: A device that measures how fast the wind is moving. It is a common weather station instrument.

Global Wind Belts *Where the convection cells meet, prevailing winds and jet streams form. *They blow from one direction over a certain area of the Earth’s surface

Prevailing Winds *Named for the direction from which they flow. Polar Easterlies – High latitudes blow east to west toward the equator. Westerlies – Mid latitudes blow west to east toward the poles. Easterlies (trade Winds) – low latitudes blow east to west toward the equator.

Jet Stream *Forms high in the upper troposhere between two air masses of different temperatures *Higher temperature differences = faster speed Due to the coriolis effect (the winds curving around the earth due to its rotation), the jet stream 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.

Global Winds and Ocean Currents A. Coriolis Effect 1. The effect the Earth’s rotation has on the atmosphere and oceans. a. The Earth rotates from east to west (counterclockwise) which causes a slight deflection in global patterns. b. This deflection is toward the right (west) in the northern hemisphere and to the left (southern) in the southern hemisphere.

1. El Nino is seasonal ocean current. a. Is caused by unusually higher water temperatures in the equatorial Pacific Ocean. b. It flows southward along the coast of Northern Peru. c. It is associated with atmospheric changes due to fluctuations in ocean-current patterns. d. It is also warm, nutrient poor and low in salinity.

La Nina Current: 1. Unusually cooler than normal ocean temperatures in the eastern equatorial Pacific. 2. Brings nutrients for fish and increased levels of oxygen. 3. Usually brings wetter weather which is opposite of El Nino

Deep Ocean Currents: 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.

What influences weather? Weather – describes the state of the air at a particular place and time ex: warm or cold Climate – the average or typical weather conditions observed over a long period of time for a given area. ex: tropical areas are hot and humid a. Humidity – amount of water vapor in a gaseous state found in the air; measure of moisture 3. Jet stream - a current of fast moving air found in the upper levels of the atmosphere.