Global Air Circulation

Identify the latitudes where bands of clouds tend to exist all year long.

Near 60ο latitude Along the equator

Which "Earth" below has two large atmospheric circulation cells, one in each hemisphere where the air rises at the equator before traveling to each pole where it descends?

Nonrotating Earth

Which of the following accurately states a reason for the difference in temperate range of oceans compared to continents?

The mixing of ocean waters helps moderate the temperature of the atmosphere over the ocean.

In each hemisphere on Earth, there are _____ atmospheric large-scale convection cells oriented in a north-south direction.

3

What is a convection cell?

A large-scale circulation pattern composed of an ascending limb of air and a descending limb of air connected by horizontal winds

Select the large-scale air movements that occur in the Hadley cell in the Southern Hemisphere.

Air ascends near the equator in the Southern Hemisphere. Low-altitude winds blow to the north toward the equator.

Why are dry conditions prevalent at 30ο N and S latitude?

Air is descending and warming here. This makes condensation unlikely as relative humidity decreases.

If Earth did not rotate, what would the large-scale atmospheric circulation pattern be?

Air would rise near the equator, travel to the poles aloft, where it would descend and then travel back to the equator as surface wind.

How is atmospheric circulation related to solar radiation?

Atmospheric circulation moves absorbed solar energy (heat) toward the poles and returns cooled air towards the equator.

What is the name given to a large-scale loop of circulating air?

Convection cell

In the Northern Hemisphere, the ________ cell is the continuous atmospheric convection cell that has an ascending limb near the equator and a descending limb near 30ο latitude. The columns of vertical movement are connected by south-moving winds at low altitudes and north-moving winds at high altitudes.

Hadley

Select the large-scale movements of air that occur in the Ferrel cell.

High- and low-altitude winds blow air toward high latitudes. Air ascends near 60ο N and S.

In the nonrotating Earth model, air flows directly toward high latitudes once it stops rising near the equator. How does Earth's rotation change this airflow for the Northern Hemisphere?

It causes the northward moving air to be continuously deflected to the east until it is flowing almost directly eastward.

Why is the range of atmospheric temperatures over continents greater than it is over the oceans?

Land surfaces heat up or cool off more quickly than water does.

Why do temperatures decrease with increasing latitude?

Sunlight strikes Earth less directly at higher latitudes, which results in less energy reaching Earth's surface.

Once air at the equator rises in the nonrotating Earth model, it will move aloft directly toward either pole. However, on our rotating Earth, the air is deflected from this path to the right or left (depending on the hemisphere) until it is flowing almost directly on an east-west path around 30ο latitude. Why does this deflection occur?

The Coriolis effect deflects the air until is flowing along an east-west path.

Which of the following statements accurately reflects the long-term stability of climate on Earth?

The climate of every region on Earth has changed often.

What factors contribute to the formation of the equatorial band of low pressure?

The high levels of solar radiation received The release of latent heat as condensation occurs

Why is there an equatorial low-pressure system?

The high levels of solar radiation warm the air, which causes it to rise and form the low-pressure band near the equator.

What is climate?

The weather conditions for a region averaged over several decades

Which of the following accurately describes the overall circulation of air in the troposphere in each hemisphere?

There are three convections cells, with each occupying about 30 degrees of latitude.

The bands of air pressure tend to align ______ lines of latitude.

along; Reason: High pressure zones tend to be located at 30ο latitude and the poles. Low pressure zones are found at the equator and 60ο latitude.

Zones of low pressure exist along the equator and 60° North and South latitude, so it makes sense that bands of _____ are common here because the lifting air and condensation necessary for their formation are too.

clouds

Solar radiation causes more heating of the atmosphere at lower latitudes. This results in atmospheric circulation patterns that moves ______.

cooled air toward the equator excess heat to higher latitudes

The air that descends from the upper troposphere at 30ο N and S latitude forms a high-pressure zone at these latitudes and results in ______.

dry conditions as the already dry air descends and warms, thereby further lowering the air's relative humidity

The midlatitude convection system with descending air near 30ο latitude and ascending near 60ο latitude is known as the ______ cell.

ferrel

_____ pressure zones tend to be located at 30ο latitude and the poles. _____pressure zones are found at the equator and 60ο latitude.

high low

What explains the occurrence of the subtropical jet streams? They form from the air traveling ______.

in the upper troposphere that has been deflected from an original north-south flow to an east-west flow by the Coriolis effect

How do the westerlies form? They form as ______.

low-altitude winds in the Ferrel cell move toward higher latitudes and are deflected to the east by the Coriolis effect

The air that moves away from equatorial regions once it has ascended to the upper troposphere in the low-pressure zone is deflected by the Coriolis effect until it is flowing nearly in an east-west direction and forming the ______ jet streams.

subtropical

Some of the air that descends at 30ο N and S latitude is redirected as surface winds toward the equator. These deflected winds are called ______ winds.

trade

The air that descends in the high-pressure system near 30ο latitude is deflected toward either higher or lower latitudes once it reaches lower altitudes. If the air is moved toward higher latitudes, it will be deflected to the east by the Coriolis effect and formed into the ______.

westerlies