Meteorology Lecture Notes PDF

**LECTURE-1 METEOROLOGY, FISHERIES METEROLOGY, NATURE OF ATMOSPHERE** **Meteorology** Greek word "Meteoro" means 'above the earth's surface' (atmosphere) "logy" means "science". Branch of science dealing with that of atmosphere is known as meteorology. It is the study of lower atmosphere extending...

**LECTURE-1 METEOROLOGY, FISHERIES METEROLOGY, NATURE OF ATMOSPHERE** **Meteorology** Greek word "Meteoro" means 'above the earth's surface' (atmosphere) "logy" means "science". Branch of science dealing with that of atmosphere is known as meteorology. It is the study of lower atmosphere extending up to 20km from earth's surface where frequent physical process takes place. Meteorology is a combination of both physics and geography. This science utilizes the principles of Physics to study the behaviour of air. It is concerned with the analysis of individual weather elements for a shorter period over a smaller area. In other words, the physical state of the atmosphere at a given place and time is referred to as "weather". The study of weather is called 'meteorology'. It is often quoted as the "physics of atmosphere". **Definition of Meteorology:** Meteorology is the science that deals with the study of the atmosphere. - Weather: Physical state of the atmosphere at a given place and given time - Climate: Long term regime of atmospheric variables of a given place or area **Divisions of Meteorology:** 1. **Marine Meteorology** - Meteorology pertaining to the sea and ocean is called Marine Meteorology 2. **Aeronomy**- The science of Aeronomy investigates both the chemical and physical properties of the atmosphere and the changes that occur in these as the result of external and internal forces.6 3. **Bio-meteorology**- The scientific study of the interactions between living organisms and their atmospheric environment called biometeorology **Difference between weather and climate** **Climate:** 1. A climate is the average weather in a given area over some time. **Weather:** 1. Weather refers to how the environment behaves, mostly in terms of its impacts on life and human habits. 2. Temperature, humidity, precipitation, brightness, cloudiness, visibility, wind, and atmospheric pressure all are factors that influence the weather daily. https://miro.medium.com/v2/resize:fit:700/1\*KR-ZuXWcFN6Q717qQZjSAg.png **Definition and scope of marine meteorology:** Marine meteorology is a branch of meteorology that focuses on studying and understanding the weather and climate patterns specific to marine and coastal areas. It deals with the atmospheric processes, phenomena, and interactions that occur over oceans and other bodies of water, including their influence on weather conditions and climate variability. The scope of marine meteorology covers various aspects related to weather and climate in marine environments. Some key areas of study and investigation within marine meteorology include: 1. [Marine Weather Forecasting:] Marine meteorologists analyze and predict weather conditions at sea, including wind patterns, wave heights, precipitation, visibility, and temperature. These forecasts are vital for maritime operations, shipping, coastal management, and marine safety. 2. [Ocean]: Atmosphere Interactions: Marine meteorology explores the interactions between the atmosphere and the underlying oceans, which significantly influence weather and climate systems. 3. [Tropical Cyclones and Hurricanes]: Understanding the formation, intensification, and track of tropical cyclones is crucial for marine meteorology. These severe weather systems pose significant risks to maritime activities and coastal regions, and studying their behavior helps in issuing timely warnings and mitigating potential impacts. 4. [Coastal Weather and Climate]: Coastal areas experience unique weather phenomena due to the proximity of land and the interaction between land and sea breezes. Marine meteorology investigates the specific characteristics of coastal weather patterns, including fog, sea breezes, coastal storms, and localized climate effects. 5. [Climate Change and Sea Level Rise]: Marine meteorology plays a role in studying the impact of climate change on marine environments. This includes analyzing changes in sea surface temperatures, ocean currents, and the potential effects of sea level rise on coastal areas and marine ecosystems. Overall, marine meteorology seeks to deepen our understanding of the dynamic and complex interactions between the atmosphere and the ocean. **Marine observations and their importance** Observations from the sea play a crucial role in various fields and provide valuable information for scientific research, operational forecasting, environmental monitoring, and decision-making. Here are some key importance's of observations from the sea: 1. [Weather Forecasting and Climate Studies:] Sea observations provide essential data for meteorologists and climatologists to analyze weather patterns, storm systems, and climate trends. They help improve the accuracy of weather forecasts, storm predictions, and long-term climate projections. 2. [Oceanography and Marine Science]: Sea observations contribute to our understanding of ocean dynamics, currents, temperature variations, and the movement of marine organisms. They help scientists study ocean circulation, upwelling events, El Niño and La Niña phenomena, and the impacts of climate change on marine ecosystems. 3. [Natural Disaster Prediction and Management:] Observations from the sea, such as ocean currents, sea level, and temperature profiles, aid in predicting and monitoring natural disasters like hurricanes, tsunamis, and storm surges. These observations are crucial for issuing timely warnings, evacuations, and disaster response planning. 4. [Maritime Operations and Safety]: Sea observations are vital for safe maritime navigation, especially in terms of weather conditions, wave height, currents, and visibility. They support the planning of shipping routes, off shore operations, and the prevention of maritime accidents. 5. [Environmental Monitoring and Conservation]: Sea observations help assess the health of marine ecosystems, monitor pollution levels, track harmful algal blooms, and study the impacts of human activities on coastal areas. 6. [Climate Change Research]: Sea observations provide critical data for monitoring and understanding the impacts of climate change on the oceans. They help track sea surface temperature rise, sea level changes, ocean acidification, and melting ice caps, contributing to the assessment of climate change trends and the development of mitigation strategies. 7. [Fisheries and Resource Management]: Sea observations aid in the study of fish populations, migration patterns, and ecosystem dynamics, supporting sustainable fisheries management. They also help assess the availability of marine resources, monitor changes in fish stocks, and guide the implementation of effective conservation measures. In summary, observations from the sea are fundamental for advancing our knowledge of weather, climate, oceanography, and marine ecosystems. They have wide-ranging applications, from improving weather forecasts to safeguarding marine life and supporting sustainable development. **Importance of meteorology in fisheries** 1. Weather Forecasting and Climate Studies 2. Oceanography and Marine Science 3. Natural Disaster Prediction and Management 4. Maritime Operations and Safety 5. Environmental Monitoring and Conservation 6. Climate Change Research 7. Fisheries and Resource Management **Composition of atmosphere** The atmosphere is described as the air that surrounds the earth. - The thickness of the earth's atmosphere is about 480 km. 99 percent of the thickness lies up to the height of 32 km from the earth. - With increasing altitude, the air pressure decreases. - The atmosphere has a mixture of gases that sustains life on earth. - The earth's gravity helps hold the atmosphere in place. - The major role of the atmosphere is to contain the entry of ultraviolet rays. As per NASA, the composition of the earth's atmosphere is as mentioned below: - Nitrogen --- 78 percent - Oxygen --- 21 percent - Argon --- 0.93 percent - Carbon dioxide --- 0.04 percent - Trace amounts of neon, helium, methane, krypton and hydrogen, as well as water vapour **Composition of the Atmosphere** The atmosphere is a layer of gas or layers of gases that envelope a planet and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. The atmosphere of earth is composed of nitrogen (78%), oxygen (21%), argon (0.9%), carbon dioxide (0.04%) and trace gases. A variable amount of water vapour is also present in the atmosphere (approx.1% at sea level) and it decreases with altitude. **Ozone Gas** - Present around 10-50 km above the earth's surface and acts as a sieve, absorbing UV (ultraviolet rays) from the sun. - Ozone averts harmful rays from reaching the surface of the earth. **Water Vapour** - Water vapour is a variable gas, declines with altitude. - It also drops towards the poles from the equator. - It acts like a blanket letting the earth from becoming neither too hot nor too cold. - It also contributes to the stability and instability in the air. **Dust Particles** - Dust particles are in higher concentrations in temperate and subtropical regions due to dry winds in contrast to the polar and equatorial regions. - They act as hygroscopic nuclei over which water vapour of the atmosphere condenses to create clouds. **Nitrogen** - The atmosphere is composed of 78% nitrogen. - Nitrogen cannot be used directly from the air. - Biotic things need nitrogen to make proteins. - The Nitrogen Cycle is the way of supplying the required nitrogen for living things. **Oxygen** - The atmosphere is composed of 21% oxygen. - It is used by all living things and is essential for respiration. - It is obligatory for burning. **Argon** - The atmosphere is composed of 0.9% argon. - They are mainly used in light bulbs. **Carbon Dioxide** - The atmosphere is composed of 0.03% carbon dioxide. - Plants use it to make oxygen. - It is significant as it is opaque to outgoing terrestrial radiation and transparent to incoming solar radiation. - It is also one of the gases responsible for the greenhouse effect. **Structure of atmosphere** On the basis of vertical temperature variation the atmosphere is divided into different layers. **Troposphere:** - Earth's troposphere extends from Earth's surface to, on average, about 12 kilometers in height, with its height lower at [Earth's poles](https://www.drishtiias.com/daily-updates/daily-news-analysis/shift-in-earths-magnetic-north-pole) and higher at the equator. - Yet this very shallow layer is tasked with holding all the air that plants need for [photosynthesis](https://www.drishtiias.com/daily-updates/daily-news-analysis/bbx11-gene-greening-of-plants#:~:text=Photosynthesis%20is%20the%20process%20by,and%20energy%2Drich%20organic%20compounds.) and animals need to breathe, and also contains about 99% of all water vapor and[ aerosols](https://www.drishtiias.com/daily-updates/daily-news-analysis/aerosol-levels-hit-20-year-low) (minute solid or liquid particles suspended in the atmosphere). - The temperature in the troposphere also decreases with height. On top of this layer is what is referred to as tropopause. - It is the densest atmospheric layer, compressed by the weight of the rest of the atmosphere above it. - Most of Earth's weather happens here, and almost all clouds that are generated by weather are found here. - Most aviation takes place here, including in the transition region between the troposphere and the stratosphere. **Stratosphere:** - Located between approximately 12 and 50 kilometers above Earth's surface, the stratosphere is perhaps best known as home to Earth's [ozone layer.](https://www.drishtiias.com/daily-updates/daily-news-analysis/recovery-of-ozone-layer) - In this region, the temperature increases with height. Heat is produced in the process of the formation of Ozone, and this heat is responsible for temperature increase. - It is nearly cloud- and weather-free, but [polar stratospheric clouds](https://www.drishtiias.com/daily-updates/daily-news-editorials/ozone-layer-preservation) (occur mainly at high latitudes during the winter) are sometimes present in its lowest, coldest altitudes. - It's also the highest part of the atmosphere that jet planes can reach. **Mesosphere:** - Located between about 50 and 80 kilometers above Earth's surface, the mesosphere gets progressively colder with altitude. - The top of this layer is the coldest place found within the Earth system, with an average temperature of about minus 85 °C (-120 °F). - The very scarce water vapor present at the top of the mesosphere forms noctilucent clouds, the highest clouds in Earth's atmosphere. - Most meteors burn up in this atmospheric layer. Sounding rockets and rocket-powered aircraft can reach the mesosphere. - The transition boundary which separates the mesosphere from the stratosphere is called the stratopause. **Thermosphere:** - It is located between about 80 and 700 kilometers above Earth's surface, whose lowest part contains the[ ionosphere.](https://www.drishtiias.com/daily-updates/daily-news-analysis/ionospheric-based-monitoring-of-large-earthquakes) - Because this layer is much closer to the sun, it can reach temperatures up to 2,000 °C (3,600 °F) - In this layer, temperatures increase with altitude due to the very low density of molecules found here. It is both cloud- and water-vapor-free. - The [aurora](https://www.drishtiias.com/daily-updates/daily-news-analysis/discrete-auroras-of-mars) borealis (Northern lights) and aurora australis (Southern lights) are sometimes seen here. - The[ International Space Station (ISS)](https://www.drishtiias.com/daily-updates/daily-news-analysis/russia-withdrawing-support-from-international-space-station) orbits in the thermosphere. **Ionosphere:** - It is not a distinct layer as the others mentioned above. Instead, the ionosphere overlaps the mesosphere, thermosphere, and exosphere. - It's a very active part of the atmosphere, and it grows and shrinks depending on the energy it absorbs from the sun. - It is an electrically conducting region capable of reflecting radio signals back to Earth. - The electrically charged atoms and molecules that are formed in this way are called ions, giving the ionosphere its name and endowing this region with some special properties. **Exosphere:** - It is located between about 700 and 10,000 kilometers above Earth's surface, the exosphere is the highest layer of Earth's atmosphere and, at its top, merges with the [solar wind.](https://www.drishtiias.com/daily-updates/daily-news-analysis/coronal-holes) - Molecules found here are of extremely low density, so this layer doesn't behave like a gas, and particles here escape into space. - While there's no weather in the exosphere, the aurora borealis and aurora australis are sometimes seen in its lowest part. - Most Earth satellites orbit in this layer.  **Layer of Atmosphere** **Temperature with Altitude** **Key Features** **Temperature Range** **Altitude Range** ------------------------- ------------------------------- ----------------------------------------- ----------------------------- -------------------------- **Troposphere** Decreases with altitude Weather, breathable air, UV protection -55 to 20 degrees Celsius 0 to 15 kilometers **Stratosphere** Increases with altitude Ozone layer, UV protection -55 to 20 degrees Celsius 15 to 50 kilometers **Mesosphere** Decreases with altitude Meteor protection -90 to -55 degrees Celsius 50 to 85 kilometers **Thermosphere** High, but thin atmosphere Satellite orbits, radio signals -55 to 500 degrees Celsius 85 to 600 kilometers **Exosphere** Virtually no atmosphere Transition to space, spacecraft passage 500 to 2000 degrees Celsius 600 to 10,000 kilometers