TCAP Review 4

Surface CurrentsSurface Currents

Horizontal movement caused by winds Horizontal movement caused by winds near the oceans surfacenear the oceans surface

Two examples: Gulf Stream and Brazil Two examples: Gulf Stream and Brazil CurrentCurrent

Three Factors: global winds, Coriolis Three Factors: global winds, Coriolis effect, continental deflectionseffect, continental deflections

Global WindsGlobal WindsWinds cause the currents to flow in different Winds cause the currents to flow in different

directions directions Equator= east to westEquator= east to westPoles = west to eastPoles = west to east

Coriolis EffectCoriolis Effect

Curving of moving Curving of moving objects from a straight objects from a straight path due to Earth’s path due to Earth’s rotationrotation

Northern hemisphere- Northern hemisphere- clockwiseclockwise

Southern hemisphere-Southern hemisphere-counterclockwisecounterclockwise

Continental Deflections Continental Deflections Currents change Currents change

directions by hitting the directions by hitting the continents or continents or landmasseslandmasses

Deep CurrentsDeep CurrentsA stream like movement of ocean water A stream like movement of ocean water

far below the surfacefar below the surfaceForm where water density increasesForm where water density increasesDecreasing water temperature and Decreasing water temperature and

increasing water salinity increase density.increasing water salinity increase density.Examples: North Atlantic Deep Water and Examples: North Atlantic Deep Water and

Antarctic Bottom WaterAntarctic Bottom Water

Deep Currents can form byDeep Currents can form byDecreasing temperatureDecreasing temperature Increasing salinity through freezingIncreasing salinity through freezing Increasing salinity through evaporationIncreasing salinity through evaporation

Currents and ClimatesCurrents and ClimatesSurface currents gently cool or warm the Surface currents gently cool or warm the

coastal areas year round coastal areas year round Some surface currents change their Some surface currents change their

circulation pattern causing changes in the circulation pattern causing changes in the atmosphere that affect the climate in many atmosphere that affect the climate in many parts of the world. parts of the world.

Warm Water Currents and Warm Water Currents and ClimatesClimates

Warm water currents create warmer climates in coastal areas.

Cold Water Currents and Cold Water Currents and ClimatesClimates

Cold water current bring cooler climates into areas.

UpwellingWhen local wind patterns blow along the northwest coast of

South America, they cause local surface currents to move away from the shore. This warm water is then replaced by deep, cold water. This movement causes upwelling to occur in the eastern Pacific. Upwelling is a process in which cold, nutrient-rich water from the deep ocean rises to the surface and replaces warm surface water. The nutrients from the deep ocean are made up of elements and chemicals, such as iron and nitrate. When these chemicals are brought to the sunny surface, they help tiny plants grow through the process of photosynthesis. The process of upwelling is extremely important to organisms. The nutrients that are brought to the surface of the ocean support the growth of phytoplankton and zooplankton. These tiny plants and animals support other organisms such as fish and seabirds.

Upwelling

UndertowWhen waves crash on the beach head-on,

the water they moved through flows back to the ocean underneath new incoming waves. This movement of water, which carries sand, rock particles, and plankton away from the shore, is called an undertow.

Longshore currentWhen waves hit the shore at an angle,

they cause water to move along the shore in a current called a longshore current. Longshore currents transport most of the sediment in beach environments. This movement of sand and other sediment both tears down and builds up the coastline. Unfortunately, longshore currents also carry and spread trash and other types of ocean pollution along the shore.

Longshore Current

Our AtmosphereThe atmosphere is a mixture of gases that

surrounds Earth. In addition to containing the oxygen you need to breathe, the atmosphere protects you from the sun’s damaging rays. The atmosphere is always changing. Every breath you take, every tree that is planted, and every vehicle you ride in affects the atmosphere’s composition.

Our atmosphereNitrogen, the most common atmospheric gas, is released when dead plants and dead animals break down and when volcanoes erupt.Oxygen, the second most common atmospheric gas, is made by phytoplankton and plants.The remaining 1% of the atmosphere is made up of argon, carbon dioxide, water vapor, and other gases.

Air pressureThe atmosphere is held around the Earth by

gravity. Gravity pulls gas molecules in the atmosphere toward the Earth’s surface, causing air pressure. Air pressure is the measure of the force with which air molecules push on a surface. Air pressure is strongest at the Earth’s surface because more air is above you. As you move farther away from the Earth’s surface, fewer gas molecules are above you. So, as altitude increases, air pressure decreases.

Layers of our atmosphere

Atmospheric HeatingThermal energy is transferred in one of three

way:RadiationConvection (circulating currents)Thermal conduction

RadiationThe Earth receives energy from the sun by radiation.

Radiation is the transfer of energy as electromagnetic waves. Although the sun radiates a huge amount of energy, Earth receives only about two-billionths of this energy. But this small fraction of energy is enough to drive the weather cycle and make Earth

habitable.

ConvectionConvection is the transfer of thermal

energy by the circulation or movement of a liquid or gas.

Most thermal energy in the atmosphere is transferred by convection. For example, as air is heated, it becomes less dense and rises. Cool air is denser, so it sinks. As the cool air sinks, it pushes the warm air up. The cool air is eventually heated by the Earth’s surface and begins to rise

again. This cycle of warm air rising and cool air sinking causes a circular movement of air, called a convection current.

Convection

Thermal conductionIf you have ever touched something hot, you

have experienced the process of conduction. Thermal conduction is the transfer of thermal energy through a material. Thermal energy is always transferred from warm to cold areas. When air molecules come into direct contact with the warm surface of Earth, thermal energy is transferred to the atmosphere

Thermal Conduction

WindThe movement of air caused by differences in

air pressure is called wind. The greater the pressure difference, the faster the wind moves. Differences in air pressure are generally caused by the unequal heating of the Earth. The equator receives more direct solar energy than other latitudes, so air at the equator is warmer and less dense than the surrounding air. Warm, less dense air rises and creates an area of low pressure. This warm, rising air flows toward the poles. At the poles, the air is colder and denser than the surrounding air, so it sinks. As the cold air sinks, it creates areas of high pressure around the poles. This cold polar air then flows toward the equator.

Wind

Pressure beltsYou may imagine that wind moves in one huge, circular

pattern from the poles to the equator. In fact, air travels in many large, circular patterns called convection cells. Convection cells are separated by pressure belts, bands of high pressure and low pressure found about every 30° of latitude, as shown in Figure 2.As warm air rises over the equator and moves toward the poles, the air begins to cool. At about 30° north and 30° south latitude, some of the cool air begins to sink. Cool, sinking air causes high pressure belts near 30° north and 30° south latitude. This cool air flows back to the equator, where it warms and rises again. At the poles, cold air sinks and moves toward the equator. Air warms as it moves away from the poles. Around 60° north and 60° south latitude, the warmer air rises, which creates a low pressure belt. This air flows back to the poles.

Pressure Belts

Global WindsThere are six types of global winds. They

are:Polar EasterliesWesterliesTradewindsDoldrumsHorse LatitudesJet Streams

Local WindsLocal winds generally move short distances

and can blow from any direction. Local geographic features, such as a shoreline or a mountain, can produce temperature differences that cause local winds. During the day, the land heats up faster than the water, so the air above the land becomes warmer than the air above the ocean. The warm land air rises, and the cold ocean air flows in to replace it. At night, the land cools faster than water, so the wind blows toward the ocean.

Land BreezeA land breeze is a type of wind that blows

from the land to the ocean. When there is a temperature difference between the land surface and the ocean, winds will move offshore. Although commonly associated with ocean shorelines, land breezes can also be experienced near any large body of water such as a lake. Land breezes usually occur at night. During the day, the sun will heat land surfaces, but only to a depth of a few inches. At night, water will retain more of its heat than land surfaces. Water has a high heat capacity which is one reason hurricane season officially extends through the chilly November months.

At night, the temperature of the land cools quickly without the insolation from the sun. Heat is rapidly re-radiated back to the surrounding air. The water along the shore will then be warmer than the coastal land creating a net movement of air from the land surfaces towards the ocean.

Land Breeze

Sea BreezeA sea breeze happens during the day when cool air

from the water travels to replace the warm over the land. Land heats up faster than the water. The air over the land begins to warm and since warm air is less dense than cool air, it rises as it is lighter than the cooler air above it. As the warm air rises over the land, the cooler air over the water begins to move in to replace the air that is rising over the land. This causes the wind at the surface to switch direction and blow from the water. As the afternoon wears on, the sea breeze normally strengthens and moves further and further inland. Its cooling relief can sometimes be felt many miles inland. Once the sun sets, the air over the land begins to cool and the air stops rising.

Sea Breeze

Mountain an Valley BreezesIn areas where there are mountains and valleys we

see a type of wind pattern known as mountain breezes and valley breezes. During the day, the surface of the mountain heats the air high up in the atmosphere, quicker than the valley floor can. As the warmer air expands a low pressure is created near the top of the mountain. This attracts the air from the valley, creating a breeze that blows from the valley floor up towards the top of the mountain. Often birds known as raptors, such as eagles, hawks, condors and vultures, float on these breezes to preserve their energy. This wind pattern is known as a valley breeze.

Mountain and Valley Breezes