From thunderstorms to typhoons to driving winds, the world's weather is often tumultuous, destructive, and surprising. And yet, all these phenomena represent Nature's attempt to mitigate extreme conditions. In this introduction, begin to explore some of these extremes as you examine the great complexity of the world weather system.
Why do cold and warm fronts exist? Can you dig a well so deep you cannot pump water from it? Find the answer to these and other questions as you explore three key concepts of weather:- temperature, pressure, and density; and the equation that sums up their relationship: the ideal gas law.
What is air made of? Is it always true that hot air rises and cold air sinks? Learn more about the air that surrounds us and cushions us from the outer reaches of space, and examine the various layers that make up the earth's atmosphere.
Energy radiates all around us, streaming in from sunbeams and emanating from every object on Earth. Investigate the various kinds of radiation represented on the electromagnetic spectrum, and see how these forms of energy - assisted by the greenhouse effect - make life possible on our planet.
If all the Earth receives energy from the sun, why are there such wide temperature differences across the planet? Why do we have seasons? Answer these questions while learning about how heat moves through the atmosphere via two basic processes: conduction and convection.
Gain an understanding of how wind works as you explore the way temperature and pressure drive sea breezes during the day and land breezes at night. Then apply these findings to a dramatic wind condition, the famous Santa Ana winds of California.
Add a new element to your understanding of the atmosphere—water—and learn some basic facts about air's capacity to hold water vapor, including the impact of temperature on atmospheric moisture and the implications for weather.
Why does dew form on some mornings? Why does it take longer to cook food at higher elevations? Discover the answer to these questions as you learn about saturation: the point where air holds the highest amount of water vapor that it can contain.
One of the most familiar and beautiful features of weather is the cloud. In this lecture, examine different kinds of clouds, learn how clouds are born, why and how they take their distinctive shapes, and what kinds of conditions are likely to produce clouds.
Continue your discussion of clouds as you take a closer look at the climates and precipitation relating to this weather phenomenon. Discover why some clouds produce rain while others do not and see why deserts are often found on the lee side of mountains.
Move from clouds to wind as you begin to explore how and why air is transported around the globe. Examine how conditions, including differences in air pressure and temperature as well as the rotation of the Earth, determine where winds arise and the direction in which they blow.
In addition to pressure differences and the Earth's rotational movement, two other forces help to determine the winds' strength and direction: friction and centripetal force. Learn about these two forces and examine how they shape the winds the world over.
After mastering the four forces that affect wind, step back to view their patterns of flow across the Earth's hemispheres. Examine the two models of air circulation that help account for large-scale air-circulation patterns and variations in temperature from the poles to the equator.
In this lecture, you encounter some of the most dramatic air-flow patterns found in nature, the swift, turning winds of the cyclone. Trace the lifecycle of the extratropical cyclone, which draws its power from the huge energy generated when different air masses meet.
Shift your eyes to the sky and examine what happens in a higher level of the atmosphere called the middle troposphere. With this examination, you discover two new features in large weather systems; troughs and ridges that occur in areas of very low and very high pressure, and see how these features affect the weather.
Expand your understanding of how air moves by taking a three-dimensional view of atmospheric circulation. Discover what happens when winds change direction and what conditions cause these changes in wind shear.
In this lecture, investigate how mountains can disturb the atmosphere into which they intrude from below. Also, learn how these disturbances can be felt far and wide.
That familiar crash of thunder and the torrential rains that often accompany it are common weather during the warm season. Learn how these noisy storms can form near cold fronts associated with extratropical cyclones and see how scientists use radar to study these storms.
Delve deeper into tumultuous weather as you learn about the formation of towering supercell storms. You also take a detailed look at how the conditions that produce these storms can lead to deadly tornadoes.
With their massive volume and constantly moving currents, oceans provide a vast reservoir of energy. Explore how the winds help generate movement in the ocean and, in turn, how the oceans affect weather all over the world, creating a huge feedback loop that helps create our climate.
Building on your understanding of how the ocean affects weather, turn your attention to the tropical cyclone, generally known as the hurricane or typhoon. Examine the typical structures of the tropical cyclone, and investigate the conditions needed to unleash these dangerous storms.
Here, you bring together all you've learned in earlier lectures about the composition of air, the electromagnetic spectrum, the condensation of liquid, and the role of oceans in our climate, and use that information to explore two dazzling phenomena: light and lightning.
Scientists have learned a lot about how weather works and have developed sophisticated tools to predict what may happen in our weather. You learn about the sophisticated numerical models these experts use, as well as the inevitable limitations of those models.
Despite all their knowledge and tools, scientists cannot make perfect predictions. Find out why, using the example of Hurricane Rita in 2005, and explore the deep complexity of weather and climate that makes the subject of meteorology one that continues to fascinate.
