Science Review Project

By: Aaliyah, Chloe, Sarita, & Mathew

Air Masses/Fronts:(Chloe)

Air Mass- A large amount of air that has a similar pressure, temperature, and moisture level.

There are four main types of air masses: Maritime, Continental, Polar, and Tropical. The Maritime Air Mass is formed over or near water, and is very moist. The Continental Air Mass is formed over land, and has very little if any moisture. The Polar Air Mass is located by the poles, and is very cold. The Tropical Air Mass is located near the equator, and is warm. There are different types of combinations that can be made depending on where the air mass originates. If the air mass is over water and near the poles, it would be called a Maritime Polar Air Mass. If the air mass is over water and near the equator, it would be called a Maritime Tropical Air Mass. If the air mass is over land and near the poles, it would be called a Continental Polar Air Mass. If the air mass is over land and near the equator, it would be called a Continental Tropical Air Mass. We use symbols to represent these different combinations. A lowercase letter is used to tell the overall moisture of the air mass, and a capital letter is used to tell the temperature or thermal properties of the air mass.

Air Masses (symbols & descriptions):

Maritime Polar: (mP) wet and cold

Maritime Tropical: (mT) wet and warm

Continental Polar: (cP) dry and cold

Continental Tropical: (cT) dry and warm

Front- The boundary between an air mass where weather occurs.(usually stormy and cloudy areas)

There are four main types of fronts: Cold Front, Warm Front, Occluded Front, and Stationary Front. A Cold Front forms when a cold air mass pushes a warm air mass up. The weather during a cold front consists of: heavy rain, thunderstorms, and snow storms. A Warm Front forms when a warm air mass stretches over a cold air mass. The weather during a warm front consists of: drizzle, fog, light rain, and a little snow depending on where the front is located. An Occluded front happens when a fast moving cold front moves through a slow, warm front. This front causes a lot of rain. A Stationary Front happens when a warm air mass and a cold air mass meet but neither is strong enough to move the other. At stationary fronts there might be some drizzle, fog, or grey skies.

Weather Fronts-

Symbols for Fronts:

Cold Front:

Warm Front:

Occluded Front:

Stationary Front:

Local Winds/Pressure:(Mathew)

Land Breeze-a breeze blowing toward the sea from the land, especially at night, owing to the relative warmth of the sea.

>A land breeze occurs when the land and sea are cooling, but the land is cooling faster. So the air above the land cools faster then that of the ocean cause the air above land have a lower pressure then the sea. This causes the air to blow towards the low pressure area and creates a land breeze

Sea Breeze-a breeze blowing toward the land from the sea, especially during the day owing to the relative warmth of the land.

>A sea breeze occurs during the day when the land and sea are both heated by the sun, but the land is heated faster. This cause the air over the land to be warmer than the air over the ocean. This causes a pressure gradient which causes wind to blow from the sea to the land (High pressure to low Pressure).

High pressure and low pressure- High-a condition of the atmosphere in which the pressure is above average. Low-a condition of the atmosphere in which the pressure is below average.

> High pressure and low pressure are usually explained when it comes to weather. High pressure systems cause good weather which includes sunny weather and slightly cloudy skies. Low pressure systems cause bad weather including thunderstorms, rain, and even tornadoes. The reason the weather changes like this is because when air rises it gets more moist and when it sinks it dries and warms. High pressure systems sink when low pressure systems rise so thats why people talk about low pressure meaning bad weather.

Convection Currents In The Atmosphere: (Sarita)

Convection- The transfer of heat. It also describes the process affecting the atmosphere, water and solid earth. In the atmosphere hot air rises on convection currents, circulating and creating clouds and winds. This is what keeps the ocean temperature stable. Convection can also be used to describe plate movement. Convection happens naturally on warm sunny days . As the earth absorbs the suns energy certain parts absorb more than others; also known as uneven heating. As the warm air becomes more dense and sinks the cold air becomes lighter. Thermals transfer heat into the atmosphere causing cooler, heavier air to replace it. As the cool air rises it is heated and rises as a thermal. This process is known as circulation or thermal cell, it causes clouds. These clouds move horizontally because of winds and continue to transfer heat. This is called advection.

Coriolis Effect- The rotation of the earth has an interesting, confusing effect on free moving objects on earth. Objects in the Northern hemisphere go to the right, well objects in the Southern hemisphere go to the left. So basically the coriolis effect tries to force things to the right or left. Sometimes the coriolis effect can cause winds to work against the pressure gradient. The pressure gradient causes winds to be pushed outward while the coriolis effect pushes it left or right. Most times these two forces are balanced, causing the winds to blow sideways along the pressure gradient. This is known as geostrophic wind.

Trade Winds- Trade winds are movements of air towards the equator. They are warm steady breezes that the coriolis effect forces to the west. It will look this way if they are coming from north and south. Between thirty and sixty degrees (latitude) the winds curve east. Because winds are named from where they originate, these are called prevailing westerlies. These winds in the northern hemisphere are responsible for many of canada and our own weather. About sixty degrees in both hemispheres the westerlies are joined by the polar easterlies, reducing upward motion. These easterlies form when the atmosphere over the poles cool. This air then sinks and spreads over the surface. As the air flows away from the poles it turns to the west because the coriolis effect.

Doldrums- Doldrums is an area of calm weather where the trade winds meet. This causes upward winds to form as they are heated so there are no steady surface winds. So it’s basically a belt of calm light winds between northern and southern trade winds of the Atlantic and Pacific.

Jet Stream- Jet streams are currents of air found in the atmosphere at about 12 km above the surface of earth. They form boundaries with differences in temperature. Because of the earths rotation, the stream/currents flow west to east going slower than the actual wind in the stream.

Convection Cells- Convection cells are a result of the process where hot air (water) rises and cool air (water) sinks, replacing it. This cycle is never ending. A sea breeze is an example of convection cells because water can hold heat better than land. Meaning when the sun rises the air on land warms up more quickly than the land over water. A low density area forms over water, beginning the process.

Convection Currents In the Ocean:(Aaliyah)

Convection - The circulation of fluids caused by warmer less dense materials rising and cooler more dense materials sinking. Dependent on temperature and amount of salt in the water.Cold sinks … Heat raises

Temperature - The earth heats from its core. So when the cold water sinks it causes the the warm water to be pushed to the surface. Since the surface is cooler the water that was once warm becomes cold and sinks to the down pushing the once cool but now warm water to the top this process continues to repeat itself.

Salinity - Amount of salt in the water plays apart in convection currents because of density. The more dense something is it sinks and the less dense something is it floats. So the cold water is full of salt , causing the water to be more dense and sink. When the water gets close to the earth is it heats up causing the salt to, in a way, evaporate. This means the warm water will be less dense causing it to rise. The heating and cooling of the water exchanging positions causes circulation or Convection Currents.

El nino- First noticed by fisherman near the coast in South America in the 1600s because of warm water in the Pacific Ocean around December. El nino is caused by large amounts of ocean and atmosphere interaction and effects sea temperatures in the central and east central Equatorial Pacific.

La nina- Sometimes referred to as to as El Viejo, anti- El nino, or a cold event is a period of below average sea temperatures across the east central Equatorial Pacific. La nina usually affects the opposite region of el nino.

Gyre- A large system of circular ocean currents. the movement of gyre helps the ocean conveyor belt which regulates temperature, salt levels, and nutrients in the ocean. Gyre are caused by wind patterns, earth rotation, and land masses. the water circulates in the direction the wind is blowing. There are 3 major types of gyre’s. Tropical, subtropical, and subpolar.

There are 5 major gyre’s in the world.

Indian Ocean Gyre

North Atlantic Gyre

North Pacific Gyre

South Atlantic Gyre

South Pacific Gyre

Comment Stream