Britannica Student Encyclopedia - 2010

18), automobiles became easier to operate

and more comfortable. Steel bodies

and heaters became common.

AfterWorldWar II (1939–45) automakers

began using power steering, power

brakes, and automatic controls for windows

and seats. Air conditioning also

became available.

In the late 1950s, European compact

cars like the Volkswagen Beetle caused a

sensation. U.S. makers built their own

compact cars starting in 1959.

The Problem of Oil

The gasoline used in automobiles comes

from petroleum (oil). As the United

States began to use up its own oil

supplies, it looked to other countries for

more. In 1973 the oil-producing

countries stopped shipping as much oil

to the countries that needed it. This

caused high prices and long lines at gas

stations. It also made automakers work

to produce cars that did not use as much

gasoline. Japanese companies were

especially successful at this.

Automobiles also cause air pollution. As

gasoline is burned it produces harmful

gases. Some scientists blame these gases

for a problem called global warming. By

the 21st century some automakers had

created vehicles that combined gasoline

and electric power.

Safety

Early cars were very dangerous to ride

in. Since then automobile manufacturers

have worked to create safer cars. They

installed such devices as seatbelts and air

Hybrid cars use less gasoline than other

cars. They rely on an electric motor for part

of their power.

BRITANNICA STUDENT ENCYCLOPEDIA Automobile 237

 

bags to protect riders in a crash. They

have also tried to improve the way cars

are built so that the cars will survive a

crash better.

#More to explore

GlobalWarming • Internal-Combustion

Engine • Petroleum • Pollution • Road

Avalanche

An avalanche is a large amount of snow

that quickly moves down a slope. An

avalanche can be deadly because it will

bury or sweep away anything in its path.

Large amounts of sliding earth or other

materials may also be called avalanches.

But these are often known as landslides.

Many different conditions make an avalanche

possible. An avalanche is more

likely to happen on a slope without trees

or large rocks. These things help to keep

snow in place. A weak layer of snow also

makes an avalanche likely. For example,

melting and refreezing may cause a layer

of snow to become slick. Snow piling on

top of this weak layer can easily slide off.

Heavy snowfall, strong wind, and rising

temperature all can start an avalanche.

Falling rocks or ice also can cause snow

to slide. Even the movement of a skier

or a snowmobile can begin an avalanche.

#More to explore

Landslide • Snow

Avocado

Although many people think that avocados

are vegetables, they are actually

fruits. An avocado is a berry with one

large seed, or pit, in the center.

There are more than 1,000 varieties of

avocado. Avocado trees grow wild in

Mexico and in Central and South

America. American Indians in those

areas developed some avocado varieties

thousands of years ago. Today farmers

grow avocados in many places with mild

winters and plenty of sun.

Avocado trees have broad, shiny leaves

that stay green all year. The trees can

grow up to about 65 feet (20 meters)

tall. Their fruits are round or pearshaped.

They vary widely in size. On the

outside the fruits are green or dark

purple. The greenish or yellowish flesh

inside turns soft after picking.

Avocados are rich in fat, protein, and

several vitamins. They can be eaten raw.

Mashed avocado is the main ingredient

in the Mexican sauce called guacamole.

Axum

#see Aksum.

People in

mountainous

areas protect

themselves

from avalanches

in several

ways.

Special fences

hold snow in

place. Barriers

also help to

stop sliding

snow.

The avocado is a fruit with a large seed

inside.

238 Avalanche BRITANNICA STUDENT ENCYCLOPEDIA

 

Azerbaijan

The country of Azerbaijan sits at the

crossroads between central Asia, Europe,

and the Middle East. The capital is

Baku.

Azerbaijan is bordered by Russia, Georgia,

Armenia, and Iran. The Caspian Sea

lies to the east. A part of Armenia separates

the Azerbaijani republic of

Nakhichevan from the rest of Azerbaijan.

The Caucasus Mountains run through

northern and southern Azerbaijan. The

central area is a large plain crossed by

the Kura River. Most of Azerbaijan is

dry, with hot summers and mild winters.

The region has many earthquakes.

Most of the country’s people are Azerbaijani,

though there are a few Russians,

Armenians, and other minority groups.

Most people speak Azerbaijani, a Turkic

language. More than 90 percent are

Muslims. However, the people of the

Nagorno-Karabakh region (an area also

claimed by Armenia) are mostly Eastern

Orthodox Christians. About half of the

people live in cities.

Azerbaijan’s economy is based on its

natural resources and agriculture. Its

major resources are petroleum (oil) and

natural gas. Crops include grains, vegetables,

fruit, sugar beets, cotton,

tobacco, and tea. Sheep, goats, and

cattle provide wool and meat. Manufacturers

make mainly food and petroleum

products.

Azerbaijan’s written history is more than

2,000 years old. At various times Arabs,

Persians, Turks, and Mongols dominated

the land. Russia took over Azerbaijan in