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Semester 2: Core Course CLIMATOLOGY
Scope and Content Weather and Climate Climatic Elements- Atmospheric Composition and Structure Insolation and Temperature Factors and Distribution, Heat Budget, Temperature Inversion
Scope and Content Weather and Climate Climatic Elements
Atmospheric Composition and Structure
The atmosphere is composed of layers including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. Each layer has distinct characteristics in terms of temperature, pressure, and composition. Key components of the atmosphere include nitrogen, oxygen, carbon dioxide, argon, and water vapor, which play crucial roles in weather and climate.
Insolation and Temperature
Insolation refers to the amount of solar energy received at a particular location. Factors affecting insolation include latitude, season, cloud cover, and atmospheric conditions. Temperature distribution across the Earth is influenced by these factors, affecting weather patterns and climatic zones.
Factors and Distribution
Various factors influence climate distribution, including geography, altitude, ocean currents, and prevailing winds. Human activities also impact local and global climates through greenhouse gas emissions and land-use changes.
Heat Budget
The heat budget illustrates the balance between incoming solar radiation and outgoing heat energy from the Earth. This balance is crucial for maintaining global temperatures. Changes in the heat budget due to natural phenomena or human actions can lead to climate change.
Temperature Inversion
Temperature inversions occur when a layer of warmer air traps cooler air at the surface, often leading to fog and air pollution. These inversions can significantly affect local weather conditions and air quality.
Atmospheric Pressure and Winds Planetary Winds, Forces affecting Winds, General Circulation of Air, Jet Streams
Atmospheric Pressure and Winds
Atmospheric Pressure
Atmospheric pressure is the weight of air above a given point. It decreases with altitude due to the thinning of air. Pressure is measured in millibars or inches of mercury. Standard atmospheric pressure at sea level is approximately 1013.25 mb.
Planetary Winds
Planetary winds are large-scale wind patterns that occur due to Earth's rotation and the differential heating of the Earth's surface. They are influenced by the Coriolis effect, trade winds, westerlies, and polar easterlies. These winds play a crucial role in weather and climate.
Forces Affecting Winds
The primary forces affecting winds include pressure gradient force, Coriolis force, and friction. The pressure gradient force drives air from high to low pressure areas, the Coriolis force affects wind direction due to Earth's rotation, and friction slows winds, particularly near the Earth's surface.
General Circulation of Air
The general circulation of air refers to the large-scale movement of air around the planet, which involves the Hadley cells, Ferrel cells, and polar cells. These circulation cells contribute to the distribution of temperature and moisture across the Earth's surface.
Jet Streams
Jet streams are fast-flowing air currents found in the upper levels of the atmosphere. They typically flow from west to east and influence weather patterns. There are two main types: the polar jet stream and the subtropical jet stream, each playing a role in storm development and movement.
Air Masses- Classification of Air Masses Fronts - Classification of Fronts
Air Masses and Fronts
Definition of Air Masses
Air masses are large bodies of air with uniform temperature and humidity characteristics. They form over regions where the surface conditions are relatively homogeneous. The properties of air masses are mainly influenced by the underlying surface.
Classification of Air Masses
Air masses are classified based on their source region and characteristics. The main types are: 1. Continental (c) - formed over land, generally dry. 2. Maritime (m) - formed over oceans, generally moist. 3. Polar (P) - formed in high latitudes, cold. 4. Tropical (T) - formed in lower latitudes, warm.
Movement of Air Masses
Air masses can move across the surface of the Earth and interact with other air masses and geographical features. The movement is influenced by pressure systems, jet streams, and local topography.
Definition of Fronts
A front is a boundary between two different air masses. Fronts are important in meteorology as they often lead to significant weather changes.
Classification of Fronts
Fronts are classified into several types based on the interaction of the air masses: 1. Cold Front - occurs when cold air advances and pushes into warmer air. It can lead to thunderstorms and a drop in temperature. 2. Warm Front - occurs when warm air rises over cold air. It is associated with gradual weather changes and can bring prolonged precipitation. 3. Stationary Front - occurs when neither air mass is advancing, leading to prolonged wet weather. 4. Occluded Front - occurs when a cold front overtakes a warm front, leading to complex weather patterns.
Atmospheric Moisture Evaporation, Humidity, Condensation, Fog and Clouds, Precipitation Types
Atmospheric Moisture Evaporation, Humidity, Condensation, Fog and Clouds, Precipitation Types
Evaporation
Evaporation is the process where liquid water is transformed into water vapor. It occurs when water molecules gain enough energy to break free from the liquid state. Factors influencing evaporation include temperature, humidity, wind speed, and surface area.
Humidity
Humidity refers to the amount of water vapor present in the air. It can be expressed as absolute humidity (mass of water vapor per unit volume of air), relative humidity (percentage of moisture relative to the maximum capacity of the air), and specific humidity (mass of water vapor per mass of air). High humidity can lead to discomfort and impacts weather patterns.
Condensation
Condensation is the process in which water vapor cools and changes back into liquid water. This process is critical in cloud formation and occurs when air is cooled to its dew point. It releases latent heat, which can influence atmospheric stability.
Fog and Clouds
Fog is a type of cloud that forms at or near the ground, resulting in reduced visibility. It is formed when air is cooled to its dew point, leading to condensation. Clouds, on the other hand, are formed at various altitudes when moist air rises, cools, and condenses into water droplets or ice crystals. There are various types of clouds classified based on their shape and altitude.
Precipitation Types
Precipitation is any form of water that falls from the atmosphere to the Earth's surface. Common types include rain (liquid water droplets), snow (ice crystals), sleet (frozen ice pellets), and hail (larger ice balls). The type of precipitation is influenced by atmospheric conditions, particularly temperature and the processes occurring in clouds.
Cyclones Tropical Cyclones, Temperate Cyclones, Monsoon - Origin and Mechanism, El Nino La Nina
Cyclones Tropical Cyclones, Temperate Cyclones, Monsoon - Origin and Mechanism, El Nino La Nina
Tropical Cyclones
Tropical cyclones, also known as hurricanes or typhoons, form over warm ocean waters in the tropics. They develop from clusters of thunderstorms when specific atmospheric conditions are met, including warm sea surface temperatures, high humidity in the mid-troposphere, and low wind shear. The mechanism involves the transfer of heat from the ocean surface, causing warm, moist air to rise. As the air rises, it cools and condenses, releasing latent heat, which further fuels the cyclone's growth. These cyclones are characterized by a low-pressure center, strong winds, and heavy rainfall.
Temperate Cyclones
Temperate cyclones, also known as mid-latitude cyclones, occur in the temperate zones and are associated with the meeting of cold and warm air masses. These cyclones typically form along the polar front, where the warm air from the tropics meets the cold polar air. This convergence leads to the lifting of air, cloud formation, and precipitation. The mechanism involves a mixing of air masses with differing temperatures and humidity levels, creating fronts: warm fronts and cold fronts. The movement of these cyclones is influenced by the jet stream.
Monsoon
Monsoons are seasonal winds that cause significant changes in precipitation patterns. In Asia, the southwest monsoon occurs when warm, moist air from the Indian Ocean moves over the land, bringing heavy rainfall. The onset of the monsoon is marked by the development of a low-pressure system over the Indian subcontinent, drawing in moist air. The mechanism involves a complex interaction between land and ocean temperatures, and the differential heating leads to variations in pressure, causing the winds to change direction.
El Nino
El Nino is a periodic climatic phenomenon characterized by the warming of surface waters in the central and eastern tropical Pacific Ocean. This warming disrupts normal weather patterns, leading to significant global climate effects, such as increased rainfall in some regions and droughts in others. El Nino alters atmospheric circulation, impacting jet streams and weather conditions worldwide.
La Nina
La Nina is the counterpart of El Nino and involves the cooling of surface waters in the central and eastern tropical Pacific Ocean. This phenomenon typically leads to opposite effects of El Nino, with drier conditions in some regions and increased rainfall in others. La Nina can enhance hurricane activity in the Atlantic and influence global weather patterns, contributing to varied climatic conditions.
