Category Weather & Climate

WHAT IS HUMIDITY?

When water evaporates it forms the gaseous water vapour. The amount of water vapour in the air at any one time is known as its humidity. AS more and more water vapour saturates the air, humidity increases, eventually resulting in rain, fog or mist, depending on the heat and temperature of the place.

Humidity is the amount of moisture or water vapour or water molecules present in the atmospheric gas. The more water in the vapour, the higher the humidity. Humidity arises from water evaporating from places like lakes and oceans. Warm water evaporates quickly. That’s why; you may find the most humid regions near to warm water bodies in places like the Red Sea, the Persian Gulf, and Miami.

Types of Humidity:

  1. Relative humidity: A meteorologist uses the term ‘relative humidity’. The relative humidity is a comparison of the amount of moisture present in the air to the amount of moisture air can hold. The amount of moisture the atmosphere can hold totally depends on the temperature.
  1. Specific humidity: We define specific humidity as the mass of water vapour present in a given unit mass of moist air.

Specific humidity is equal to the ratio of water vapour mass and the air parcel’s total (including dry) air mass.

Specific humidity is also known as the humidity ratio. It does not change with the expansion or compression of an air parcel.

We usually express specific heat as grams of vapour per kg of air, or in air conditioning as grains per pound.

The specific humidity has great usage in meteorology.

3. Absolute humidity: We define the absolute humidity in the two following sentences:

Absolute humidity is equal to the mass of water vapour per unit of volume of air, i.e., grams of water/cm3 of air. The formula for the absolute humidity is given by:

             Absolute humidity = Mass of water/volume in cm3

Absolute humidity does not take temperature into consideration.

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WHY ARE LATITUDE AND LONGITUDE IMPORTANT?

Two points on Earth can lie at the same latitude but still be far away from each other. Similarly, two distant points may lie on the same longitude. But only one point lies on a particular combination of latitude and longitude. So latitudes and longitudes are necessary for locating an exact point on Earth.

The importance of longitude and latitude are:

  • Latitudes help in identifying and locating major heat zones of the earth.
  • Latitude measures the distance between the north to south from the equator.
  • Latitude helps in understanding the pattern of wind circulation on the global surface.
  • Longitude measures the distance between the west to earth from the prime meridian.
  • Both longitude and latitude help us measure both the location and time using a single standard.
  • The lines of longitude and latitude help us in measuring the distance from the Earth’s Equator
  • Latitudes help us to find out the distance of any place from the Equator, which is base on its degree of latitude.
  • Longitude and latitude help us to find the location of any place on earth. These coordinates are what the Global Position System or GPS

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What is the purpose of climate fiction?

Cli-fi or Climate fiction has gained traction over the past few years. It turns the spotlight on issues relating to climate change and the fall-out of human activity on the environment and the future of our planet.

Commenting on Jim Laughters Polar City Red, a novel set around climate refugees in a future Alaska, Dan Bloom, a freelance writer coined the term cli-fi. In his description of the genre, Bloom calls it a route to wake people up through storytelling.

Climate fiction or Climate change fiction, popularly abbreviated as Cli-Fi modelled after the assonance of Sci-fi (Science fiction), is literature that deals with global warming and climate change. Not necessarily speculative in nature, the works of cli-fi may take place in the world as we know it or in the future.

Where to get started with climate fiction?

Although the term Cli-fi came into use in the late 2000s to describe novels and movies that deal with man-made climate change, historically there have been any number of literary works that have thematically dealt with climate change as a natural disaster. Some important books from this genre are:

Parable of the Sower by American writer Octavia E. Butler

It is probably the quintessential Cli-fi book. Published in 1993, it narrates the story of Lauren Olamina, a young girl growing up in California in the years 2024-2027. Our protagonist suffers from a debilitating disability called hyper-empathy which makes her extremely sensitive to the emotions of other people.

Set in a time when climate change and disease outbreaks have increased social disorder, this novel follows Lauren in her quest for freedom. Several characters from various walks of life join her on her journey north and learn of a religion she has crafted titled Earthseed. This religion emphasises the idea that one’s final mission in life is to inhabit other planets.

Parable of the Sower has won multiple awards, including the 1994 New York Times Notable Book of the Year, and has been adapted into a concert and a graphic novel.

The MaddAddam Trilogy by Margaret Atwood

Set in a darkly plausible future shaped by plagues, floods, and genetic engineering these books talk about the price of development. This trilogy comprises Ong and Crake (2003). The Year of the Hood (2009). and MaddAddam (2013)

Oryx and Crake begins with Jimmy or snowman waking to a desolate world. A reality where humankind has been nearly destroyed by a 21st Century plague spread through a health supplement called BlyssPluss pill The Year of the flood tells the other side of the story and gives us the view from the wildemess where God’s gardeners struggle to lead non-violent lives in a degraded landscape. MaddAddam the final book in the series brings together survivors from both the previous books looking towards the possibility of regeneration.

Gun Island by Amitav Ghosh The book Deen, a New York-based antiquarian book dealer who goes into the Sundarbans, the (disappearing) wetlands wedged between India and Bangladesh, in search of a shrine and the truth behind the myth of the Gun Merchant and Manasi Devi, the goddess of snakes.

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Which is the largest hot desert?

The Sahara in North Africa is the largest hot desert and the third largest desert in the world. Spread over an area of 9.4 million sq km, the desert covers large sections of as many as 11 countries such as Egypt Libya. Tunisia, Algeria, Morocco and Sudan. Did you know only one quarter of the desert is sandy? The rest is made up of rocky plateaus, gravel, salt flats, dry valleys and oases.

The Sahara is bordered by the Atlantic Ocean to the west, the Red Sea to the east, the Mediterranean Sea to the north and the Sahel savanna to the south. The enormous desert spans 10 countries (Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan and Tunisia) as well as the territory of Western Sahara, a former Spanish colony that was annexed by Morocco in 1975, though control of the region is disputed by the Indigenous Saharawi people.

The Sahara desert has a variety of land features, but it is most famous for the sand dune fields that are often depicted in movies. The dunes can reach almost 600 feet (183 meters) high, and they cover about 25% of the entire desert, according to the Encyclopedia Britannica. Other topographical features include mountains, plateaus, sand- and gravel-covered plains, salt flats, basins and depressions. Emi Koussi, an extinct volcano in Chad, is the highest point in the Sahara, reaching 11,204 feet (3,415 m) above sea level,  and the Qattara Depression in northwestern Egypt is the Sahara’s deepest point, at 436 feet (133 m) below sea level.

Despite the harsh, arid conditions of the Sahara, many plant and animal species call the region home. Approximately 500 plant species, 70 mammalian species, 90 avian species, 100 reptilian species and numerous species of spiders, scorpions and other small arthropods live in the Sahara. The camel is one of the most iconic animals of the Sahara, though its ancestors originated in North America. Other mammal residents of the Sahara include gazelles, addaxes (a type of antelope), cheetahs, caracals, desert foxes and wild dogs. Many reptiles also thrive in the desert environment, including several species of snakes, lizards and even crocodiles in places where there is enough water. Several arthropod species also call the Sahara home, such as dung beetles, scarab beetles, “deathstalker” scorpions and many types of ants.

Today, the Sahara has a dry, inhospitable desert climate. The past 2,000 years or so, the climate of the Sahara has been fairly stable — and dry. The northeastern winds strip moisture from the air over the desert and drive hot winds toward the equator.

Credit : Live science

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WHAT MAKES THE SEASONS?

Earth is always tilted the same direction as it orbits the Sun. So when Earth is on one side of the Sun, the northern hemisphere is tilted closer towards the Sun, making it warmer. At the same time, the southern hemisphere is tilted away from the Sun, and is, therefore, colder. When Earth reaches the other side of the Sun, it is the opposite, so it’s winter in the northern hemisphere and summer in the southern.

Seasons happen at different times in different parts of the world. The tilt of the Earth doesn’t change as it rotates around the Sun. But the part of the planet that gets the most direct sunlight does change.

The Northern Hemisphere is tilted away from the Sun from September to March. That means the northern half of the planet doesn’t get as much light and heat from the Sun. This causes autumn and winter. During the same months, the Southern Hemisphere is tilted towards the Sun. That means the southern half of the planet gets spring and summer.

From March to September, the Northern Hemisphere is tilted towards the Sun. So that’s when the northern half of the Earth experiences spring and summer. During the same months, the Southern Hemisphere experiences autumn and winter.
Other planets also have seasons. But the length and intensity of each season varies from planet to planet.

  • On Earth, seasons last between 90 and 93 days.
  • On Venus, seasons last between 55 and 58 days.
  • On Mars, seasons change about once every six months. Summer lasts 199 days and winter lasts 146 days.
  • On Saturn, seasons last about seven years.
  • And if you lived on Neptune, you would have to wait more than 40 years for the seasons to change!

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WHAT IS THE PRIME MERIDIAN?

This is an imaginary line of 0° longitude that is perpendicular to the equator, and parallel to the axis. It passes through Greenwich in the UK, and divides Earth into eastern and western hemispheres. As it crosses the poles to the opposite side of the globe, the line becomes 180° longitude and is also known as the International Date Line.

The prime meridian is arbitrary, meaning it could be chosen to be anywhere. Any line of longitude (a meridian) can serve as the 0 longitude line. However, there is an international agreement that the meridian that runs through Greenwich, England, is considered the official prime meridian.

Governments did not always agree that the Greenwich meridian was the prime meridian, making navigation over long distances very difficult. Different countries published maps and charts with longitude based on the meridian passing through their capital city. France would publish maps with 0 longitude running through Paris. Cartographers in China would publish maps with 0 longitude running through Beijing. Even different parts of the same country published materials based on local meridians.

Finally, at an international convention called by U.S. President Chester Arthur in 1884, representatives from 25 countries agreed to pick a single, standard meridian. They chose the meridian passing through the Royal Observatory in Greenwich, England. The Greenwich Meridian became the international standard for the prime meridian.

Credit: National geographic

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