CSIR NET Earth Science Mock Test - 3 - CSIR NET Earth Science MCQ

A particular colour is produced by reflection of some and absorption of other components of white light.

Choice of the right method will, therefore, be possible only when the nature of the rocks and the ground all along the alignment is fully known. This is one of the most important aim and object of geological investigations.

Models are useful to understand Earth. Scientists, who study about atmospheres, use the atmosphere model. Like this, scientists who study oceans, use the ocean model.

Some scientists study both the atmosphere and ocean; use the coupled ocean-atmosphere model.

This coupled ocean-atmosphere model is useful in seasonal prediction of the monsoon, ENSO prediction, climate prediction. There are many models for predicting the path of a tropical cyclone like NWP model, GFS model.

A coupled ocean-atmosphere model is not essential for this.

Permeability of a rock measures the ability of a porous material to allow fluids to pass through it.

It depends on the size of the rock, interconnection, distribution, and volume of the pores of the rock.

The permeability of some rocks in increasing order of permeability is given below:

Gulf streams are warm currents, which originate in the Gulf of Mexico from north equatorial current and move in north easterly direction along the eastern coast of North America and reaches the western coasts of Europe near 70^oN latitude.

Brazil current is a warm current, which originate in the Brazilian coast near Sun Rock from south equatorial current and moves southward along the east coast of South America upto 40^oS latitude.

Kuroshio is a warm current, which originates near Philippines from north equatorial current and moves in north easterly direction along the eastern coast of Asia towards pole.

Agulhas current is warm current, which originates near Madagascar from south equatorial current and moves southward along the eastern coast of Madagascar and joins Mozambique current up to the southern tip of the southern tip of Africa and ultimately diverted eastward.

The Mariana Trench or Marianas Trench is the deepest known part of the world’s oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about 2,550 kilometres long with an average width of 69 kilometres.

The Ninety East Ridge is a linear, age-progressive seamount chain in the Indian Ocean and is named for its near-parallel strike along the 90th meridian at the center of the Eastern Hemisphere.

The Carlsberg Ridge is the northern section of the Central Indian Ridge, a divergent tectonic plate boundary between the African Plate and the Indo-Australian Plate, traversing the western regions of the Indian Ocean.

Bermuda Rise is a cluster of extinct volcanoes in the Atlantic Ocean, including the island of Bermuda.

A zone of low-pressure builds up over NW India as a result of excessive solar radiation. With the advance of the monsoon this heat low gradually extends eastward until it forms an elongated low-pressure roughly parallel to the southern foothills of Himalayas. This refers as monsoon trough.

X-ray diffraction or XRD analysis or XRPD analysis is a unique method in determination of crystallinity of a compound. XRD is primarily used for

ID of crystalline material (for regulatory purposes or during development)

ID of different polymorphic forms (“fingerprints”)

Distinguishing between amorphous and crystalline material

Quantification of the percent crystallinity of a sample

The diffraction from ideal crystalline substances are characterized by Bragg peaks (plots the energy loss of ionizing radiation during its travel through matter) in X-ray diffraction.

The crystalline substances have long range order.

The amorphous substances do not possess this long range order.

So the diffraction from them do not show sharp Bragg peaks.

Bragg peak for protons, α-rays, and other ion rays occurs immediately before the particles come to rest.

Tidal range varies due to changes in the position and alignment of the Moon and Sun relative to Earth. Every 15 days, the largest tidal ranges in semi-diurnal regions occur during spring tides, when the Moon and Sun are in phase around times of new or full Moon; while the smallest tidal ranges occur during neap tides, when the Moon and Sun are out of phase.

In diurnal regions, the largest tidal ranges occur every 15 days during equatorial tides, when the Moon is over the tropics while smallest tidal ranges occur during tropic tides, when the Moon is over the equator.

Tidal range changes as the Moon moves from its closest (perigee) approach to Earth, to its furthest approach (apogee) and back when we discuss about in a month’s time.

Annually, tidal range changes occur as the Sun’s position varies north or south of the equator, and as it moves from its closest to furthest approach to Earth and back. The largest semi-diurnal tidal range occurs during the equinoxes (March and September), while the largest diurnal tidal range occurs during the solstices .

Headward erosion is erosion at the origin of a stream channel, which causes the origin to move back away from the direction of the stream flow. So, it causes the stream channel to lengthen. It also increases the length of a valley and a canyon. It also increases the sinuosity of a drainage divide.

When sheets of water on a roughly planar surface first enter a depression in it, this erodes the top edge of the depression.

Ocean information is collected using different types of remote sensing techniques such as optical, thermal, and microwave. Infrared sensors give information about sea surface temperature. Satellites are useful tools for observing the earth and the ocean that covers more than 70% of the planet.

By remote sensing data collected from their orbits high above the earth, satellites provide us much more information than would be possible to obtain merely from the surface.

Information gathered by satellites can tell us about ocean bathymetry, sea surface temperature, ocean colour, coral reefs, and sea and lake ice.

Hardness measures the strength of the structure of a mineral relative to the strength of its chemical bonds.

The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.

It was created in 1812 by German geologist and mineralogist Friedrich Mohs.

The correct sequence of mineral according to the Mohs scale of hardness is:

The temperature read by a thermometer covered in water soaked cloth over which air is passed. Getting the wet bulb temperature involves isobaric and adiabatic process. If wet-bulb temperature cools adiabatically to saturation by evaporation of water into it, all latent heat being supplied by the volume of air. Thermodynamic wet bulb temperature can be referred as isobaric wet-bulb temperature. The relationship between the isobaric and adiabatic processes is quite obscure.

Earth’s magnetic field is the magnetic field that extends from the Earth’s interior out into space.

In the southern hemisphere, Earth’s magnetic field is negative and in northern hemisphere, it’s positive.

Magnetic field has horizontal and vertical components.

In southern hemisphere, horizontal component is positive.

The modification of air masses occurs as they move away from their source region. In the source region air masses gain properties, which are the characteristic of the underlying surface.

They may be cold or warm and it may also be dry or moist. The stability of the air can also be derived. The more unstable an air mass is, the more likely we are to experience unsettled weather such as wind or rain.

As an air mass moves from its source region the air is modified due to variations in the nature of the underlying surface. Two important processes that may modify an air mass are:

According to the classification of tropical storms by the World Meteorological Organization, several categories of storm and their maximum sustained wind speeds are given as:

ITCZ is a low pressure belt, encircles Earth near Equator where the trade winds of the Northern and Southern Hemispheres come together. The position of ITCZ varies with the seasons.

ITCZ propagates poleward more prominently over land than over oceans because water has a higher heat capacity than land. So, ITCZ propagates more over Northern Hemisphere than Southern Hemisphere. In July and August, ITCZ is between 5 and 15°north of the equator. But it is further more over the land masses. Over the Indian region it is farthermost of about 30° .

• The inversion increases in thickness and gains height towards the lower latitudes
• Considerable cloud development can take place below the inversion layer.
• The inversion is due to the subsidence associated with the sub-tropical highs.

As per Koeppen Classification:

• Aw = Tropical Savanna. Hot, seasonally dry (usually winter)
• Cwb = Tropical upland. Cold winter
• Cfa = Humid subtro- pical. Mild winter; moist all season; long hot summer
• BSh = Tropical steppe; semi-arid; hot
• Cwa = Tropical upland. Mild winter; dry winter; short warm summer

One of the eddy motions in the mid-latitude is mid latitude cyclones.

These result from baroclinic instability.

Baroclinic conditions are usually found in the midlatitudes for large scales while barotropic conditions are found in the tropics.

In baroclinic conditions, density is a function of pressure and temperature i. e. , the density and temperature vary along a pressure surface.

The Bergeron- Findeisen process is cold-rain process. This process of droplet growth involves ice-crystal growth in mixed phase clouds. This process is much more efficient in producing large particles than smaller ones.

Collision and coalescene mechanism is important for forming raindrops in warmer clouds.

The continued growth of a cloud droplet, once condensation has started, is initially governed by the diffusion of the water vapor molecules toward the droplet.

As condensation proceeds, these droplets grow, coalesce with neighboring drops, and may fall-off or start to slide down the cold wall.

The Madden–Julian oscillation (MJO) is the largest element of the intraseasonal (30 to 90 day) variability in the tropical atmosphere. It is a large-scale coupling between atmospheric circulation and tropical deep convection.

(ENSO) is an irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting climate of much of the tropics and subtropics. The warming phase of the sea temperature is known as El Nino and the cooling phase as La Nina.

The movement of meanders must be accompanied by the movement of sediment. A dominant discharge is defined as the discharge that transports the most sediment over a long time period.

Dominant discharge may be computed by combining information from a daily sediment-rating curve and a discharge-duration curve. Information on suspended sediment load is generally available, therefore suspended sediment can be considered.

Thus, it is necessary to assume that the total sediment load is proportional to the suspended load. Dominant discharge is responsible for the development of the meander pattern of a river.

Cumulus clouds are called fair weather clouds. Clouds can be classified into three types on the basis of heights as above ground level at which they form. They are:

The unit hydrograph theory was pronounced by Le-Roy K. Shermen in 1932. It is the unit pulse response function of a linear hydrologic system.

The unit hydrograph of a watershed is defined as a direct runoff hydrograph resulting from 1 inch (1 cm in SI units) of excess rainfall generated uniformly over the drainage area at a constant rate for an effective duration.

Sherman used the word unit to denote a unit of time. Since it has often been interpreted as a unit depth of excess rainfall.

He classified runoff into surface runoff and groundwater runoff and defined the unit hydrograph for use only with the surface runoff.

Retaining structures may prove exceptionally successful where- the ground is neither too fine nor too plastic; the sliding mass is likely to remain dry and the movement is of a shallow nature and limited extent.

The nature of slope includes two important characters of slope. By nature of slope is meant here the type of material of which the land mass is made up and the angle at which this particular mass is inclined with the horizontal.

Lightning is discharge of electricity, a giant spark, that occurs in mature thunderstorms. Lightning is actually a flow of electrical current through the air. Rain falling from a thunderstorm will often evaporate before reaching the ground (virga). Lightning then strikes dry ground, starts a fire, and there isn’t any rain to put out or at least slow the spread of the fire. The occurrence of lightning with no rain is called dry lightning. When lightning strikes the ground positive charge is deposited on the ground.