Climate and Weather

Climate and weather The atmospheric conditions of a place (such as temperature, pressure, wind, and humidity) change based on the amount of sunlight received. These are called the elements of weather. There is a clear difference between weather and climate. Weather refers to the short- term atmospheric conditions: in a specific area. These conditions include temperature, pressure, wind, and humidity. Climate is the average of weather conditions over a large area for a long period, like 35 to 40 years. Insolation The amount of solar radiation received at the Earth's surface is called insolation. Processes that heat the atmosphere Since solar radiation is in short waves, it does not directly heat the atmosphere. : The processes that transfer heat to the atmosphere include: → Conduction: The transfer of heat from the Earth's warm surface to the lower layers of the atmosphere. → Convection: It occurs when warm air near the Earth's surface expands and rises. This carries heat to higher altitudes. → Advection: The horizontal: transfer of heat through wind.: → Radiation: The process by which the Earth's surface emits longwave radiation after absorbing solar energy What is terrestrial radiation? Solar radiation passes through the atmosphere in short waves. It does not directly heat the atmosphere. However, the Earth re-emits this energy in long waves, which heat the atmosphere. This process is called terrestrial radiation. Greenhouse Effect Greenhouses are glass structures used in cold regions to protect plants. In the atmosphere, greenhouse gases like carbon dioxide absorb terrestrial radiation. This warms the atmosphere. The phenomenon is similar to what happens inside greenhouses. And hence the name. What is heat budget? Heat budget is the balance that keeps the Earth's surface temperature stable. That is, without excessive heating.or cooling. This is done through the Earth's re-radiation of heat received from the Sun. Maximum and minimum temperature, Daily range, and Daily Mean temperature → Due to heat transfer processes, the atmosphere takes time to warm up. The maximum temperature of the day is usually recorded around 2:00 PM. → The minimum temperature is recorded just before sunrise. At this time, the Earth's surface and air cool due to terrestrial radiation. → Diurnal range of temperature: The difference between the maximum and minimum temperatures of a day. → Daily mean temperature: The average of the maximum : and minimum temperatures. Isotherms Isotherms are imaginary lines: drawn on a map connecting places with the same temperatures. Atmospheric pressure It is the weight of the air exerted on the Earth's surface. → It is measured using a barometer in units of millibars or hectopascals. → Influenced by temperature, altitude, and humidity in the air. Isobars Isobars are imaginary lines drawn on maps connecting places of equal atmospheric pressure. Factors influencing temperature distribution Temperature varies across the Earth's surface due to: → Latitude → Altitude → Distance from the sea → Ocean currents → Relief (Topography) For example: → Equatorial regions are warmer; polar regions are cooler. → Temperature decreases with increasing altitude. → Coastal regions have moderate temperatures; interiors have more extreme temperatures. → Warm and cold ocean currents influence nearby land temperatures. → Slopes facing the Sun are warmer than the opposing slopes. Global pressure belts Due to solar heating and the Earth's rotation, the Earth has specific global pressure belts: 1. The Equatorial Low- Pressure Belt is caused by rising warm air at the equator. It is a windless, calm region. 2. Polar high-pressure belts are formed due to the cooling and sinking of air at the poles. 3. The subtropical high- pressure belts are formed as the air rising from the equatorial region gradually cools and descends around 30° N & S latitudes. 4. Due to the influence of Earth's rotation, the air is forced to rise on a large scale from the 60° N 4. Due to the influence of Earth's rotation, the air is forced to rise on a large scale from the 60° N & S latitudes, leading to the formation of Subpolar low-pressure belts. Why do pressure belts shift? Due to the apparent movement of the Sun: → In summer, the pressure belts shift 5° to 10° northwards. → In winter, they shift 5° to 10° southwards. Air currents and wind → Air currents: Vertical movements of air. → Wind: Horizontal movements of air.