Earth Systems: 26 MCQs with answers

The Earth's revolution around the Sun and the tilt of its axis

The Sun only appears to move north and south; this apparent movement is due to the Earth's revolution around the Sun combined with the tilt of the Earth's axis.

Circle of Illumination

The Circle of Illumination is the imaginary great circle that divides the Earth into the lit hemisphere (day) and the dark hemisphere (night).

Barometer

A barometer is the instrument used to measure atmospheric pressure, usually expressed in millibars.

Anemometer

An anemometer is the instrument used to measure the speed (and often direction) of the wind.

True

On June 21st the Northern hemisphere has its longest day (summer solstice), so the Southern hemisphere has its longest night.

False

A solar eclipse occurs when the Moon comes between the Sun and the Earth. When the Earth comes between the Sun and the Moon, it is a lunar eclipse.

The tilt of the Earth's axis

The tilt of the Earth's axis causes different parts of the Earth to receive varying amounts of sunlight throughout the year, leading to the change of seasons.

Full Moon

A Full Moon occurs when the entire face of the Moon is illuminated by the Sun, making it fully visible from Earth.

Gravitational force

The gravitational force of the Moon pulls on the Earth's water, causing tides to rise and fall.

Temperature

Temperature affects air pressure because warm air is lighter and rises, leading to lower pressure, while cold air is denser and sinks, leading to higher pressure.

Winds that blow from east to west

Trade winds are the prevailing winds that blow from east to west in the tropics, influencing weather patterns.

Desert

Deserts are regions that receive very little rainfall and can experience extreme temperatures, both hot and cold.

Coriolis effect

The Coriolis effect describes how the rotation of the Earth influences the direction of winds and ocean currents.

Front

A front is the boundary that separates two different air masses, often leading to changes in weather.

Lunar eclipse

A lunar eclipse occurs when the Earth comes directly between the Sun and the Moon, casting a shadow on the Moon.

Monsoon

Monsoons are seasonal winds that bring significant rainfall, particularly in South Asia.

The Sun's rays fall perpendicularly on the equator

At the equinoxes, the Sun's rays fall perpendicularly on the equator, so the Circle of Illumination passes through the poles and both hemispheres receive equal sunlight — making day and night equal.

Southern hemisphere

On June 21st the Northern hemisphere has its longest day (summer solstice), so the Southern hemisphere simultaneously has its longest night.

Perigee

Perigee is the point in the Moon's orbit where it is nearest to the Earth; apogee is the farthest point.

The Earth comes between the Sun and the Moon

A lunar eclipse occurs when the Earth comes between the Sun and the Moon, and the Earth's shadow falls on the Moon.

The Sun, Moon and Earth are in a straight line

Spring tides occur when the Sun, Moon and Earth are in a straight line (new moon or full moon), so the gravitational pulls of the Sun and Moon combine to produce the highest high tides and lowest low tides.

At right angles with respect to the Earth

Neap tides occur when the Sun and Moon are at right angles relative to the Earth, so their gravitational pulls partially cancel each other, producing tides of lower range.

Isobars

Isobars are lines on a map connecting places with equal atmospheric pressure; they help identify pressure belts and weather patterns.

Coriolis effect

The Coriolis effect is the apparent deflection of moving winds (and other moving objects) caused by the rotation of the Earth.

Roaring Forties

The Roaring Forties are the strong, persistent westerly winds in the southern hemisphere between about 40°S and 50°S, famous for their force.

Extremely cold climate with very short growing season and sparse vegetation

The Tundra region has an extremely cold climate, permafrost, a very short growing season, and only sparse vegetation such as mosses, lichens and small shrubs.