Unit 4 lesson 1-Elements of Weather AND lesson 2- What Influences Weather?

How does a front form?

when one air mass runs into another air mass

How do warm fronts form?

when warm air moves into an area formerly covered by cooler air

Natural Disasters

A natural event such as a flood or hurricane that causes great damage or loss of life.

When a warm air mass and a cool air mass meet, the ________________________ air mass usually moves upward.

Warm

Rainy weather at the edge of a warm front is a result of _______________________________.

Warm air rising over cold are and moisture condenses into clouds.

Warm currents have a _______________________ effect on the air masses above them.

Warming

Weather is affected by the amount of _____________________ in the air.

Water

climate

Weather conditions of an area prevailing over a long period of time.

How does an air mass form?

When air over a large region of Earth stays in one area for many days.

How does snow form?

When air temperatures are so low that water vapor turns into a solid.

How do cold fronts come form?

When cold air can quickly push up a warm air mass Since warm air is less dense than cold air.

How does sleet form?

When rain falls through a layer of freezing air, producing falling ice.

When could a stationary front become a warm or cold front?

When there is more wind to move air mass either warm air up above cold, making a cold front or if warm air mass rises over the cold air and moisture condenses into clouds, making a warm front.

How do stationary fronts form?

When there is not enough wind for either cold air mass or warm air mass to keep moving, so the two air masses remain in one place.

air-pressure diffences on a local scale affect both ___________________________.

Wind speed and wind direction at a certain location

What is the relative humidity when the air temperature is at its dew point?

100%

How fast does air move in jet streams?

92 km to greater than 180 km per hour.

How do the meanings of jet streams and global wind belts differ?

A jet stream is a fast flowing air current that occurs in the atmosphere of Earth and other planets. A global wind belt is formed by the Earth's spin and the unequal heating of the Earth via sunlight. Global winds move from the poles to the equator, whereas jet streams move from west to east horizontally

Air mass

A large volume of air in which temperature and moisture content are nearly the same throughout.

Why does air pressure decrease as altitude increases?

Air pressure & density are related; they both decrease with altitude. Molecules at sea level are closer together at seal level, so pressure is greater. Molecules at a mountain peak are father apart at the high altitude, so lower pressure.

How are puffy clouds formed?

Air that rises sharply or moves straight up and down.

How does the meanings of the terms front and air mass differ?

An air mass is a section of air with the same density and humidity, while a front is the intersection of two different air masses with differing densities

What instrument measures wind speed?

Anemomter

What instrument measures air pressure?

Barometer

Why do jet streams form?

Because Earth's surface is heated unevenly.

Why does air move from the poles to the equator?

Because air moves from areas of high pressure to areas of low pressure. At high altitudes the warmed air circles back toward the poles.

Front

Boundary between two air masses.

Clouds that are feathery or wispy and made of ice crystals. They form when the wind is strong.

Cirrus ( meaning curl of hair).

What type of weather does high-pressure system produce?

Clear skies and calm air or gentle breezes. Since air sinks and moves outwards and is denser than the surrounding air then cooler denser air moves out. As the air sinks, it gets warmer and absorbs moisture then water droplets evaporate and relative humidity decreases and clouds often disappear.

Where do the polar jet streams flow?

Closer to the poles in summer than in winter. So they can affect temperature by pulling cold air down from Canada into the U. S. And pull warm air up toward Canada.

Water vapor in the air condenses not only on Earth's surfaces, but on tiny particles in the air to form ____________________________.

Clouds

How can ocean currents raise coastal air temperatures?

Coastal cities in areas where warm ocean currents flow have warmer winter temperatures than inland cities at similar latitudes.

If the weather becomes stormy for a short time and then becomes colder, which type of front has most likely passed?

Cold front

Weather

Condition of the atmosphere at a certain time a certain place.

Water cycle

Continuous movement of water between the atmosphere, the land, the oceans, and living things.

Condensation affects weather by __________________________________

Cooling water vapor and changes from a gas to a liquid, so a change affects humidity. Also visibility when clouds and fog form.

Clouds that form in fair weather but if they keep growing taller, they can produce thunderstorms.

Cumulus ( means heap or pile)

What type of weather can you expect during a stationary front?

Days of unchanging weather, usually clear.

The air at seal level is __________________________ than air at high altitude.

Denser

How do the meanings of high-pressure system and low-pressure system differ?

First, is the circulation surrounding them. Secondly, is the atmospheric motion that they cause. Low pressure systems circulate counter-clockwise. High pressure systems circulate clockwise. These "motions" (caused by these circulations) are the building blocks in our atmosphere. They give us our weather. Low - counter-clockwise circulation forces air upward (ultimately resulting in condensation, cloud formation and ultimately precipitation). High- clockwise circulation causes a sinking motion in the atmosphere, resulting in fair/clearer and often sunnier skies.

How do ocean currents influence weather?

Flow moves energy as heat from one part of Earth to another. Warm water and cold water flow into another. Water near the equator carries energy from the sun into cooler water, changing local temperatures and humidity. Also can cause hurricanes and monsoons.

Visibility can be affected by air pollution and ________________.

Fog

When ball or lumps of ice fall from clouds during thunderstorms it is called _______________________.

Hail

Precipitation affects weather by _________________________________

Having rain, snow, sleet, or hail falling from the clouds onto Earth's surface.

If a cold front is headed to your area, what type of weather might you expect?

Heavy rain or snow and cooler weather.

Uneven heating of Earth's surface causes air pressure difference and wind. So wind moves from areas of _______________________ pressure to areas of _____________________ pressure.

Higher to lower

How can ocean currents lower coastal air temperatures?

If the coast is on a Cold-water current, it can cool the atmosphere which affect local temperatures. So coastal cities are cooler than inland cities.

How do jet streams flow?

In a wavy pattern from west to east.

How does the movement of air affect the type of weather that forms from high pressure and low pressure systems?

In high pressure systems, the cold air moves down toward the Earth's surface and then the air starts to warm up and the weather is clear. In low pressure systems, the warm air rises and gets cold, which causes the water molecules to condense and causes rain.

Evaporation affects weather by ____________________________

Increasing water vapor into the atmosphere where moisture can them be formed into clouds and then precipitation.

Air Mass

Large body of air with similar temperature and moisture.

Jet streams

Long distance winds that travel above global winds for thousands of kilometers

Temperature

Measurement of how hot or cold the air is.

What happens when air cools below its dew point?

More water vapor condenses into water than evaporates

Where do subtropical jet streams flow?

Near the equator

Where do fronts often do not occur, and why?

Near the equator because air masses there do not have big temperature differences.

Air-pressure on a global level affect ___________________________

Overall movement of surface air from the poles toward the equator.

Each hemisphere has what two main jet streams?

Polar and subtropical

What instrument measures relative humidity?

Psychrometer

When inside a cloud, droplets formed by condensation collide and form larger droplets in what common form of precipitation?

Rain

What type of weather does low-pressure systems produce?

Rainy weather Since have lower pressure than surrounding areas, air comes together and rises. As the air in the center rises and cools then forms clouds and rain.

Global wind patterns occur as, due to temperature differences, air ___________________ at the poles and ___________________ at the equator.

Sinks; rises

What are some ways to collect weather data?

Stationary- ground station and weather buoys Moving- airplanes, satellites and ships

Clouds that form in flat layers. If they are low and dark they can block out the sun & produce steady drizzle or rain.

Stratus ( means spread out)

What creates regional wind belts?

Temperature and pressure differences on Earth's surface.

Saturated air

The amount of water that evaporates equals the amount that condenses

Relative Humidity

The amount of water vapor in the air compared to the total amount of water vapor when saturated.

Humidity

The amount of water vapor in the air.

Explain how changes in weather are caused by the interaction of air masses.

The different densities of the air masses cause changes in temperature, and when these air masses interact, they create different fronts. Warm fronts increase the temperature and cause moderate precipitation, whereas cold front create heavy downpours, high winds, puffy clouds, and drops in the temperature.

Visibility

The distance one can see, that can be reduced by fog and air pollution.

Coriolis effect

The effect of Earth's rotation on the direction of winds and currents. Winds in the wind belts curve to the east or west due to the Earth's rotation.

Air Pressure

The force of air pressing down on earth's surface.

Explain how an ocean current can affect temperature and the amount of moisture of the air mass above the current and above nearby coastlines.

The ocean current can affect the temperature by either heating up the air above it when a warm current moves in, or cools the temperature down when a cold current moves in. It can also increase the humidity because water will evaporate off the ocean into the air

How does the polar jet stream affect temperature and precipitation in North America?

The polar jet stream pulls cold air down from Canada into the United States on the East Coast, and it pulls warm air from the West Coast up toward Canada. It affect precipitation patterns because strong storms ten to form around the jet stream.

Dew Point

The temperature at which the rate of condensation is greater than the rate of evaporation.

What instrument is used to measure and display temperature?

Thermometer

How are air pressure and density related?

They both decrease with altitude.

How are flat smooth clouds formed?

They cover larg ares where air rises gradually

How is wind related to the uneven heating of Earth's surfaces by the sun?

Uneven heating of Earth's surface causes pressure differences from place to place. These pressure differences set air in motion. Wind over a short distance moves directly from a higher pressure toward a lower pressure.

In a low-pressure system, air moves ____________________________.

Upward

What instrument measures wind direction?

Wind vane

Surface currents are caused by

Winds

How would winds be affected If the Earth did not rotate?

Winds would flow in straight lines.

Can jet streams predict weather?

Yes, they can affect precipitation patterns because strong storms tend to form along jet streams. And their direction can predict cold or warm air.

high pressure system

a large body of circulating air with high pressure at its center and lower pressure outside of the system. Air sinks & warms

low pressure system

a large body of circulating air with low pressure at its center and higher pressure outside of the system Air rises and cools.

Unsaturated air

more water evaporates into the air than condenses back into the water

4 types of precipitation

rain, snow, sleet, hail