UGC NET Geography 1

The north-pole lies with in the Arctic Ocean whereas south-pole is located within Antartic Continent. Which of the following theory uses this phenomenon as a supportive argument ?

(A) Theory of Isostasy

(B) Theory of Plate Tectonics

(D) Tetrahedral Theory

The answer is **(B) Theory of Plate Tectonics**.

The theory of plate tectonics states that the Earth's surface is made up of a number of large plates that are constantly moving. The North Pole lies within the Arctic Ocean because the Arctic Ocean is located on a plate that is moving away from the North Pole. The South Pole, on the other hand, is located within Antarctica because Antarctica is a continent that is not moving.

The other theories listed are not supportive of this phenomenon. The theory of isostasy states that the Earth's crust is balanced by the underlying mantle, so the North Pole would not be located in an ocean if this theory were correct. The theory of convective current theory states that the Earth's mantle is heated from below and that this heat causes the mantle to move, but this theory does not explain why the North Pole is located in an ocean and the South Pole is located on a continent. The tetrahedral theory is not a scientific theory and is not supported by evidence.

**Explanation of other theories:**

* **Theory of Isostasy** states that the Earth's crust is balanced by the underlying mantle. This means that the weight of the crust is supported by the mantle, so the crust does not sink into the mantle. The North Pole is located in an ocean because the crust in this area is relatively thin. The mantle is therefore able to push up the crust, creating an ocean.

* **Theory of Convective Current Theory** states that the Earth's mantle is heated from below and that this heat causes the mantle to move. The mantle is a layer of hot, solid rock that lies below the Earth's crust. The heat from the Earth's core causes the mantle to move in a convective current. This means that the mantle is constantly circulating, with hot material rising to the surface and cooler material sinking to the bottom. The convective current theory does not explain why the North Pole is located in an ocean and the South Pole is located on a continent.

* **Tetrahedral Theory** is not a scientific theory and is not supported by evidence. This theory states that the Earth is shaped like a tetrahedron, with the North Pole at one point of the tetrahedron and the South Pole at another point. The theory also states that the Earth's crust is made up of four plates that are constantly moving. However, there is no scientific evidence to support this theory.

Therefore, the theory of plate tectonics is the best explanation for why the North Pole lies within the Arctic Ocean and the South Pole is located within Antarctica.

🌍

Comments

Radar Remote Sensing SAR

1. Radar and Radar Remote Sensing RADAR stands for Radio Detection and Ranging . It is an active remote sensing system that transmits microwave energy toward the Earth's surface and records the energy that is returned to the sensor as an echo or backscatter . Unlike passive optical remote sensing, radar does not depend on sunlight. Therefore, it can operate day and night and, at suitable wavelengths, can acquire data through clouds, haze and light rain. Hence, radar is widely described as an all-weather, day-and-night remote sensing technology . Basic principle Microwave pulse → transmission → interaction with surface → backscatter/echo → antenna receives signal → signal processing → radar image 2. Microwave Energy Radar systems use microwave electromagnetic radiation , generally in wavelength ranges from approximately 1 mm to 1 m . Important radar bands include: Band Approx. wavelength Common applications ...

Atmospheric Window

The atmospheric window in remote sensing refers to specific wavelength ranges within the electromagnetic spectrum that can pass through the Earth's atmosphere relatively unimpeded. These windows are crucial for remote sensing applications because they allow us to observe the Earth's surface and atmosphere without significant interference from the atmosphere's constituents. Key facts and concepts about atmospheric windows: Visible and Near-Infrared (VNIR) window: This window encompasses wavelengths from approximately 0. 4 to 1. 0 micrometers. It is ideal for observing vegetation, water bodies, and land cover types. Shortwave Infrared (SWIR) window: This window covers wavelengths from approximately 1. 0 to 3. 0 micrometers. It is particularly useful for detecting minerals, water content, and vegetation health. Mid-Infrared (MIR) window: This window spans wavelengths from approximately 3. 0 to 8. 0 micrometers. It is valuable for identifying various materials, incl...

Lidar

LiDAR (Light Detection and Ranging) is an active remote sensing technology that measures distances by illuminating a target with laser pulses and analyzing the time it takes for the reflected light to return. Unlike passive systems (e.g., cameras, multispectral sensors), LiDAR provides its own energy source (laser), allowing it to operate both day and night and even penetrate through vegetation canopies . 🔹 How LiDAR Works (Step-by-Step Process) Laser Pulse Emission The system emits rapid, short pulses of laser light (commonly in the near-infrared wavelength, 1064 nm ). Some systems emit up to hundreds of thousands of pulses per second . Interaction with Target Surface The laser beam strikes objects such as vegetation, buildings, or bare ground. Depending on the object's structure, part of the pulse may scatter or reflect. Return Signal Detection The sensor records multiple returns : First Return → typically vegetation canopy tops. ...

Radar image. Polarization in Remote Sensing

L band radars operate on a wavelength of 15-30 cm and a frequency of 1-2 GHz. L band radars are mostly used for clear air turbulence studies. S band radars operate on a wavelength of 8-15 cm and a frequency of 2-4 GHz. Because of the wavelength and frequency, S band radars are not easily attenuated. . Polarization refers to the direction of travel of an electromagnetic wave vector's tip: vertical (up and down), horizontal (left to right), or circular (rotating in a constant plane left or right). . a synthetic aperture radar (SAR) for high-resolution imaging. a radar altimeter, to measure the ocean topography. echo amplitude a wind scatterometer to measure wind speed and direction. Other types of radars have been flown for Earth observation missions: precipitation radars such as the Tropical Rainfall Measuring Mission, or cloud radars like the one used on Cloudsat. . RISAT-1 (SAR, ISRO India, 2012) RORSAT (SAR, Soviet Union, 1967-1988) Seasat (SAR, altimeter, scatterometer, US, 19...

Geometric Correction

When satellite or aerial images are captured, they often contain distortions (errors in shape, scale, or position) caused by many factors — like Earth's curvature, satellite motion, terrain height (relief), or the Earth's rotation . These distortions make the image not properly aligned with real-world coordinates (latitude and longitude). 👉 Geometric correction is the process of removing these distortions so that every pixel in the image correctly represents its location on the Earth's surface. After geometric correction, the image becomes geographically referenced and can be used with maps and GIS data. Types 1. Systematic Correction Systematic errors are predictable and can be modeled mathematically. They occur due to the geometry and movement of the satellite sensor or the Earth. Common systematic distortions: Scan skew – due to the motion of the sensor as it scans the Earth. Mirror velocity variation – scanning mirror moves at a va...

Vineesh V, Geography

Search This Blog