Weather 10 Test

Air Mass

When a large portion of air is nearly uniform in temperature and humidity

How an air mass forms

When the air remains in nearly the same place long enough to take over the temperature and moisture characteristics of the land or ocean

Classifications of air mass

Continental + Maritime, Tropical + Polar

Continental air mass

Forms over land, dry air mass (lowercase when writing)

Maritime air mass

Forms over land, moist air mass (lowercase when writing)

Tropical air mass

Warm air, (uppercase when writing)

Polar air mass

Cool air (uppercase when writing)

What is a front

The zone between 2 air masses

Types of fronts

Cold, warm, stationary, occluded

Cold front

When cold air overtakes warmer air

How a cold front works

The cold air pushes the warm air up because the cold is more dense, the cold moves in below. Causes cumulus or cumulonimbus clouds, causing rain, thunderstorms, tornadoes.

Warm front

Warm air overtakes cooler air

How a warm front works

Warm air gently rides up over the trailing end of the cold air mass, stratus and nimbostratus clouds form and can bring light rain or snow lasting longer than it does with a cold front, after it passes it leave warmer temperatures than before it arrived

Statonary fronts

Cold and warm air masses are in contact but neither are moving

How a stationary front works

Warm air drifts up and condenses to form stratus clouds, and often rain, it may stay for several days, results in a dreary, gloomy sky

Occluded fronts

A cold air mass catches up with a slower-moving warm front

How an occluded front works

Many types of clouds are present, one after another, they cause periods of steady precipitation

High Pressure system

Air decends and exterts more pressure on a region below

How a high pressure system works

A air mass settles over cold ground, the air cools and becomes more dense, settles lower to the ground. Creates more pressure, so more air gets drawn in from above. Air at the bottom is forced out and to the right. This is called an anticyclone. Little moisture in high pressure sytems to create a clear sky, sometimes 100s of km across. Weather conditions stay the same for days.

Low pressure system

Very inteanse heating of the ground creates it

How a low pressure system works

Heated air rises leacing less dense air below, it pulls more air beneath it. Known as a cyclone, low is generally smaller then highs, brings unstable weather conditions, causing changing weather, precipatation, storms

Why continental air masses are dry

The air over land is typically more dry then the air over water, making those air masses take on the same characteristics, and there isn’t much moisture over land

Why are maritime air masses usually moist

The air over the ocean is typically moist because the ocean is fully water, and the water cycle makes the water always move up, along with the moisture above the water

How a cloud forms

Clouds form when invisible water vapor in the air cools and condenses into visible water droplets or ice crystals.

Things needed for cloud formation

Moisture, temperature drop, condensation nuclei

How to get temperaure drop in nature

Easiest way is by getting air to a higher altitude, when the air is warmed and it rises up, when warm air is pushed up by a cooler air mass, moving air meets a moutain range and gets pushed over it, expands, and cools. Can also be cooled by contact with a cool ground, resulting in fog.

What condensation nuclei is

They are dust, smoke, pollen, and sea salt. The average diameter is 0.01mm.

Types of clouds

Cumulus, Stratus, Cirrus, Nimbostratus, cumulonimbus

Cumulus clouds

Puffy clouds with flat bases, bringing sunny days along with it

Stratus clouds

Flat clouds, form in seemingly endless layers, cold overcast dry weather, but sometimes rainy

Cirrus clouds

High level clouds made of icy crystals, first signs of a major weather change. So high up the water vapour condenses directly into a solid by deposition

Nimbostratus clouds

Dark, thick, featurless clouds, produces steady continuous rain or snow

Cumulonimbus clouds

Dense vertical clouds, forms from moist air rising produces thunder, hail, lightning

Nimbo clouds

Means rain or snow clouds, you add to the name of the cloud. Happens with cumulus or stratus

How big rain has to be

The water droplets are mostly to small to make it to Earth, the wind makes them go flying. The ones that are 0.5mm will create a fine mist, the rain that makes it to the ground is an average of 2 mm

How rain grows to be 2mm

Clouds droplets get tossed around a lot, as a result they collide and blend together. In Canada, they turn in to ice crystals in the cold air, they collide and become snowflakes, then they melt once they get back to warmer air making rain drops

How snow is caused

If the air from the clouds all the way to the ground is below freezing point, the crystals in the clouds stay in the form of snow. If the air is very cold the crystals remain small, if the air is warmer but still below freezing, the snowflakes stick together as they fall.

How sleet is caused

Sometimes the air below the clouds are warm enough to melt the snow, turning it to rain. Then, closer to the ground, the air gets below freezing point, freezing as ice pellets called sleet

How freezing rain is formed

When rain hits cold objects, it freezes instantly, creating a solid coating of ice

How hail is formed

Starts out as frozen raindrops, then is picked up by cumulonimbus clouds, the winds carrying them into clouds. There they collide with droplets in the air that is close to freezing point. The droplets freeze immidiately, coat the hailstones. Size depends on how long it was in the clouds

Coalescene

When water droplets collide and join together

Climate Zone

A large region of the earth that has a similiar pattern of temperature, precipitation and weather over many years

Types of climates

Tropical, Dry, Temperate, Continental, Polar, Highland (Tropical Deserts Turn Cold Past Highlands)

Tropical climate

Hot all year round, near the equator, frequent rainfall ex. Brazil, Indonesia

Dry climate

Very little precipitation, includes deserts and semi-deserts ex. Sahara Desert

Temperate climate

Moderate temperatures, distinct seasons, generally mild winters ex. parts of western Europe

Continental climate

Warm summers, cold winters, large seasonal temperature differences ex. inland Canada

Polar climate

Very cold year round, short cool winters, ex. Arctic, antarctica

Highland climate

Depends on elevation for climate, cooler temperatures as altitude increases ex. Rocky Mountains, Himalayas

Temperature

The coolness or warmth of something

Precipitation

Any liquid or solid form of water that falls to Earth from the atmosphere, including rain, snow, hail

Atmospheric pressure

The force of the atmosphere on the surface below it

Humidity

The amount of water vapour in the air

Wind Speed + Direction

How quickly moving air is travelling and the direction from which it originates

Sky Cover

The portion of the sky that is covered by clouds

Why dark surfaces absorbs the energy more

Dark absorbs the energy, while light surfaces reflects the energy.

Albedo

How much energy something reflects High=lots of reflection

Incoming Radiation

Energy from the sun that has small, shortwave radiation. ex. UV lights, infrared. It is the solar energy that enters Earth’s atmosphere. 42% is absorbed, reflected, scattered by clouds, gasses, dust, smog, mist, aerosols. 49% is absorbed by land and ocean. 9% is reflected back by Earth’s surface.

Outgoing radiation

Energy that leaves Earth’s atmosphere, with long wave lengths reflected. ex. greenhouse gas, thermal. Clouds and earths surface reflects the solar energy back to space, the dust particles scatter sunlight, resulting in blue daytime. Higher up there are less things to reflect, so the light fades to black. All solar energy eventually gets radiated back to the Sun

Heat Sink

Any substance that can absorb and retain a “pool” or reservoir of energy without changing it’s state. Water is a great heat sink.

Radiation

A way of energy transfer where atoms or molecules give off energy in the form of electromagnetic waves

Conduction

The transfer of thermal energy between two substances in direct physical contact. The energy always moves from a substance with a high temperature to the substance with a lower temperature.

Convection

The transfer of thermal energy by movement of heated material from one place to another.

Humidity

A measure that describes the amount of water vapor in the air. Humid air exerts less pressure than dry air, making the air lighter.

Dew Point

The air becomes saturated when the specific humidity equals the capacity of air to hold water of a specific temperature. Aka the temperature that it reaches when there is 100% humidity

Relatative humidity

Comparing the amount of water vapor in the air to the amount it could hold is it was totally saturated

Dew point vs Relatative humidity

Dew point is the temperature and humidity is what we feel everyday