Earth Science - Class VII

Moraines are ridge-like depositional features of glacial tills. They are long but narrow ridge with height more 30 meters. Moraines are consist of rock materials of heterogeneous shapes and size.

Sea beaches are not the erosional feature of sea waves. They are formed due to the depositional activities of sea waves.

The seasons are caused by the tilt of the Earth's rotational axis away or toward the sun as it travels through its year-long path around the sun.

Latitude is a measure of the distance you are located from the equator.  It is commonly shown as an imaginary horizontal line that goes across the earth on maps and is used along with longitude as a reference point to determine location. The tilt of the earth affects the seasons we experience throughout the year.

The earth moves around the sun in an elliptical fashion, and one complete orbit around the sun take one year. An interesting fact is that it is not the proximity of the earth to the sun that determines the season; we are actually closest to the sun in January, not July.  Instead, the tilt of the earth is the key. When the Northern Hemisphere is tilted towards the sun, the Southern Hemisphere is tilted away from the sun. This leads to summer in the Northern Hemisphere and winter in the Southern Hemisphere as the Northern Hemisphere experiences the most direct sunlight and solar heating.

Temperature decreases with an increase in altitude. The reason or this is:

The ground absorbs more radiation from the sun and during night time the ground emits this absorbed radiation to its surroundings. The molecules of air surrounding the land also absorb the emitted radiation from the ground. At locations near sea level where air is most dense the air is very warm at sunset and a few hours after sunset.

At higher altitudes, the air get very rarified i.e. less dense. The less-dense air can seldom absorb the heat emitted by the ground because they are very far apart. The net result is a drop in temperature at higher altitudes.

As a summary, the decrease in temperature is due to the very less heat energy absorbed by the air molecules and the very far distance of air molecules from each other.

C. The tilt of Earths Axis

Seasons happen because Earth's axis is tilted at an angle of about 23.4 degrees and different parts of Earth receive more solar energy than others. Because of Earth's axial tilt, different areas of Earth point toward or away from the Sun at different times of the year. Around the June solstice, the North Pole is tilted toward the Sun and the Northern Hemisphere gets more of the Sun's direct rays. This is why June, July and August are summer months in the Northern Hemisphere. At the same time, the Southern Hemisphere points away from the Sun, creating winter during the months of June, July and August. Summer in the Southern Hemisphere is in December, January, and February, when the South Pole is tilted toward the Sun and the Northern Hemisphere is tilted away.

The temperature depends on latitude because when you are closer to the equator it's hotter, but whenever closer to the arctic circles it will be colder.

 At the equator there are no seasons because each day the Sun strikes at about the same angle. Every day of the year the equator receives about 12 hours of sunlight.

A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth, and moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.

A total lunar eclipse has the direct sunlight completely blocked by the earth's shadow. The only light seen is refracted through the earth's shadow. This light looks red for the same reason that the sunset looks red. Because of its reddish color, a total lunar eclipse is sometimes called a blood moon.

D. The tilt of the earth's axis of rotation

Seasons happen because Earth's axis is tilted at an angle of about 23.4 degrees and different parts of Earth receive more solar energy than others. Because of Earth's axial tilt (obliquity), our planet orbits the Sun on a slant which means different areas of Earth point toward or away from the Sun at different times of the year. Around the June solstice, the North Pole is tilted toward the Sun and the Northern Hemisphere gets more of the Sun's direct rays. This is why June, July and August are summer months in the Northern Hemisphere. At the same time, the Southern Hemisphere points away from the Sun, creating winter during the months of June, July and August. Summer in the Southern Hemisphere is in December, January, and February, when the South Pole is tilted toward the Sun and the Northern Hemisphere is tilted away.

Apollo 11 blasted off on July 16, 1969. Neil Armstrong, Edwin Aldrin and Michael Collins were the astronauts on Apollo 11.

Four days later, Armstrong and Aldrin landed on the moon. They landed on the moon in the Lunar Module. It was called the Eagle. Collins stayed in orbit around the moon. On July 20, 1969, Neil Armstrong became the first human to step on the moon.

Neil Alden Armstrong was an American astronaut and the first person to walk on the Moon. He was also an aerospace engineer, naval aviator, test pilot, and university professor.

Solar eclipses are dangerous because the sun can come out from behind the moon and surprise you before you have a chance to look away. And this is actually even worse than when you normally look away from the sun because during the total eclipse, it is dark out, and your pupil therefore dialates so that it can let in enough light to get a good picture. Then, when the sun reappears and starts flooding the area with really bright light, not only are you staring straight at it, but your eye is in a state where it is wide open, and actively trying to let in as much light as possible.

This explains why it is easy to damage your eye when watching a total solar eclipse, and why you should either be sure to time it very carefully or just view the thing through one of those sets of cheap dark glasses they sell for the express purpose of looking at the sun without getting hurt.

Marina Beach in Chennai is the longest natural urban beach in India and one of the longest in the world.

Paleomagnetic data from the Indian subcontinent shows that it was once part of Gondwana and drifted northwards over millions of years to collide with the Eurasian plate. This movement is a well-established fact in plate tectonics.

The Western Ghats are an escarpment formed by the faulting and subsequent subsidence of the western part of the Indian peninsula during the breakup of Gondwanaland. This created the steep western face of the mountains.

The presence of marsupial fossils in Asia provides evidence that these animals, now primarily found in Australia, once inhabited a broader range when the continents were connected. This supports the theory of continental drift and ancient land bridges.

Deccan Traps are Cretaceous-Eocene (3), Western Ghats are Late Cenozoic (1), Aravalli are Pre-cambrian (2), and Narmada-Tapi deposits are Pleistocene (5). Option B correctly maps these geological periods to the features.

The horizontal and vertical movements caused by the forces coming from the origin of the earth are known as endogenic forces. The origin of the endogenic force is caused by the contraction and expansion of rocks due to variation in thermal conditions and temperature inside the earth.

As seen from the Earth, a solar eclipse is a type of eclipse
that occurs when the Moon passes between the Sun and Earth, and the Moon fully
or partially blocks the Sun. This can happen only at new moon when the Sun and
the Moon are in conjunction as seen from Earth in an alignment. In a total
eclipse, the disk of the Sun is fully obscured by the Moon. In partial and
annular eclipses, only part of the Sun is obscured.

The Hemispheres of the Earth in geography and cartography refer to any division of the globe into two hemispheres. The most common such divisions are by latitudinal or longitudinal markers:

North-South

Northern Hemisphere, the half that is north of the equator

Southern Hemisphere, the half that lies south of the equator,

East-West

Eastern Hemisphere, the half that lies east of the prime meridian and west of the 180th meridian

Western Hemisphere, the half that lies west of the prime meridian and east of the 180th meridian