Chapter 12: Atmospheric Circulation and weather over SA

• Weather forecasting involves predicting future weather conditions based on current observations, historical data, and atmospheric models.

  
• The South African Weather Service (SAWS) is responsible for providing meteorological services to the public.
• Forecast accuracy depends on factors such as the quality of input data, model resolution, and initial conditions.
• The SAWS provides daily forecasts through various media channels such as radio, television, newspapers, websites, and mobile apps.
• The South African Weather Service (SAWS) is responsible for providing accurate and timely weather information to the public through various channels such as radio broadcasts, television news bulletins, newspapers, websites, mobile apps, social media platforms, and SMS services.
• Seasonal forecasts can be made up to three months ahead using statistical methods or climate models.

  
• The SAWS issues daily weather reports that include temperature, wind speed and direction, precipitation probability, cloud cover, visibility, and other meteorological parameters.
• Short-term forecasts are more accurate than long-term ones due to greater uncertainty in longer time periods.
• Forecast accuracy depends on factors like the quality of input data, model resolution, and skill level of forecasters.
• Climate change affects seasonal forecasts by altering temperature patterns and precipitation regimes.
• Several types of weather systems can be identified using satellite imagery, including frontal systems, occluded fronts, warm conveyors, cold conveyors, tropical cyclones, and anticyclonic systems.
• Synoptic charts are used to show the distribution of pressure systems, wind direction and speed, temperature, humidity, cloud cover, precipitation, and other meteorological variables at specific times.
• The SAWS uses different types of weather maps to display weather patterns and trends, including synoptic charts, satellite images, radar imagery, and numerical weather prediction models.
• Climate change refers to changes in climate patterns that occur over time scales ranging from decades to millions of years.
• Seasonal forecasts are issued four times per year by the Climate Systems Analysis Group at the Council for Scientific and Industrial Research (CSIR).
• The SAWS also issues warnings and advisories during severe weather events such as thunderstorms, heatwaves, droughts, floods, and tropical cyclones.
• Short-term forecasts are issued up to seven days ahead, while long-term forecasts cover periods beyond one week.
• Long-range forecasts are less reliable due to the complexity of the atmosphere and its interactions with other systems.
• Weather forecasting involves predicting atmospheric variables at different timescales based on current observations and past trends.
• Short-term forecasts are issued every six hours and provide detailed information about expected weather conditions within the next few days.
• Accuracy of short-term forecasts decreases with increasing lead time.
• Weather forecasting involves predicting future atmospheric conditions based on current observations and historical data.
• Short-term forecasts have higher reliability than long-term forecasts because they rely more heavily on observed data and recent trends.
• The SAWS uses numerical weather prediction (NWP) models to generate forecasts by solving equations describing the atmosphere's behavior.
• Meteorologists use mathematical equations and computer models to simulate how the atmosphere will behave under different scenarios.
• Weather forecasts are important for agriculture, tourism, transportation, energy production, emergency response planning, and other sectors.
• Long-range forecasts have lower skill levels compared to short-range forecasts.
• Longer term forecasts are issued monthly and provide an overview of anticipated weather patterns over several weeks or even months.

  
• Weather forecasting involves predicting atmospheric conditions based on current observations and historical patterns.
• Frontal systems occur when two air masses with different temperatures meet, resulting in clouds, rainfall, thunderstorms, and strong winds.
• Accurate weather forecasts require reliable observations from ground stations, satellites, radars, buoys, and aircraft.
• Weather maps are essential tools for understanding atmospheric circulation patterns and predicting future weather conditions.
• Observations from satellites, radars, buoys, and ground stations are used to gather real-time data about air pressure, temperature, humidity, winds, clouds, and precipitation.
• Data assimilation techniques combine observational data with numerical models to improve forecast accuracy.
• Different types of weather maps include surface analysis charts, upper air charts, satellite imagery, radar imagery, and numerical weather prediction (NWP) models.
• Global warming is an increase in average global temperatures due to human activities such as burning fossil fuels and deforestation.
• Occluded fronts form when an advancing cold front catches up with a retreating warm front, leading to heavy snowfall and severe storms.

  
• Weather maps are created from synoptic charts and display information about atmospheric conditions such as isobars (lines connecting points with equal air pressure), isotherms (lines connecting points with equal temperatures), and isohyets (lines connecting points with equal rainfall).
• Isallobar diagrams illustrate changes in barometric pressure over time and indicate areas where winds will converge or diverge.
• Weather is defined as the state of the atmosphere with respect to its effects on life and human activities.