The Online Guide to... The Weather

Weather: What Is It?

The fact that we have weather at all is dependent on the existence and nature of Earth's atmosphere. A unique feature of the blanket of air that envelopes our planet is the presence of water vapor, and a temperature profile that makes it possible for this water to exist in three forms: gas, liquid, and solid.

Are Accurate Forecasts Possible?

Countries almost the world invest in weather research, thinking that the dividends of accurate forecasts will far outweigh the costs. The more industrialized nations of North America, Europe, Asia, and Australasia have put together highly advanced weather services.

Air Pressure & Convection

It has been stated elsewhere in this series of articles on weather that if the Earth had no atmosphere, then we would have no weather. Just for the sake of argument, imagine an Earth with an atmosphere like we have today, but without a sun. If there were no sun, there would be no weather (and not just because the atmosphere would likely be frozen solid).

What’s the Difference Between Weather and Climate?

Weather is what results when a huge complex system (the Earth's atmosphere) reacts to the effects of an outside source (the sun), while encountering random factors (friction with geography) and limiting factors (gravity).

Earth’s Multi-Layered Atmosphere

Without the atmosphere that envelopes the Earth, we would not have weather. Indeed, we would roughly certainly not exist. The atmosphere contains oxygen that is necessary for life. It also contains water vapor, which is a crucial component of weather.

Cloud Formation

Clouds are produced when condensation occurs above ground level. If the surrounding air temperature is above freezing, water vapor condenses into droplets of water. If the air temperature is below freezing, water vapor may change directly (sublimate) into ice crystals. In some cases, water vapor can remain as a liquid in a supercooled state below freezing.

Classifying Clouds

Technically speaking, clouds are the evidence of rising air masses and condensing water vapor. Weather forecasters and observers can deduce current and future weather events based on cloud shapes.

Colors in the Sky

Weather results from the complex and never-ending interaction of the sun's heat and the Earth's atmosphere. Weather systems and storm features can often produce astounding colors in the sky. Yet, the atmosphere itself is colorless. How are these astonishingly varied colors produced?

The Coriolis Effect

The heat of the sun & the Earth's atmosphere interact on a continuous basis to produce weather. Uneven heating causes a complex system of wind flows. There are three major circulations of air that result from solar heating of the atmosphere.

Frontal Systems

Heat from the sun is constantly interacting with the Earth's atmosphere. The irregular heating of the atmosphere coupled with the atmosphere's "desire" to maintain equilibrium results in the movement of large air masses, leading to different types of weather.

Global Climate Zones

Humans have always sought to understand & explain our world. Weather and climate are no exception. As our understanding of weather patterns and longer term climate patterns has increased, we have devised a classification scheme to summarize planetary climate zones.

Global Wind Patterns

Weather is a result of the interaction between heat from the sun & the Earth's atmosphere. The uneven heating of the atmosphere coupled with the atmosphere's drive to maintain equilibrium results in the movement of large air masses, leading to different types of weather.

In the Eye of the Storm

Hurricanes are some of nature's most destructive storms. Yet, tropical storms like hurricanes are essential for maintaining equilibrium in the atmosphere. At the center of the hurricane is the eye, an area of relative calm that also happens to be the storm's area of lowest pressure.

Weather & the Land

Earth's global weather originates in large scale interactions between the sun, the atmosphere, and the rotation of the Earth itself. But the ground that this weather moves over can also have significant effects on the weather. Local and large-scale weather systems alike are affected by the different properties of land and sea.

Lightning and Thunder

Lighting is the powerful result produced by the buildup of opposite electrical charges in a thunderstorm. The electrical discharge emits bright visible light and the electrical current heats the air and expands it into plasma, producing the acoustic shock waves that we hear as thunder.

Monsoons, Sea Breezes & Chinooks

The heat of the sun, the Earth's atmosphere, the tilt of the Earth on its axis, and the Earth's rotation combine to form a complex, interdependent system. It produces the rising and falling of large air masses and the creation of cyclonic flows. We observe these massive movements of air as wind.

Inescapable and Uncontrollable

Dare I say it? Every person talks about the weather, but nobody does anything about it. It's a common saying and one that is at least partially true. Weather is a subject of nearly constant conversation and speculation. Millions search the internet every month looking for more information about local weather, world weather, and even weather disasters.

Precipitation

Clouds are formed when air rises and cools to the point where it is saturated with water vapor. When this happens, water vapor condenses into tiny droplets of water or sublimates into tiny ice crystals.

Weather & the Sea

Oceans cover more than 70 percent of the Earth's surface. Seawater stores heat efficiently and it both heats up and cools down more slowly than land surfaces. These properties mean that ocean currents can carry warm or cold water to many different parts of the Earth.

The Effect of Seasons and Cycles

Weather results from the irregular interaction of the sun with Earth's atmosphere. Significant variations in the amount of solar energy reaching our atmosphere occur as the Earth spins on its axis and, at the same time, completes its annual journey roughly the sun.

The Life Cycle of Thunderstorms

Thunderstorms are dramatic weather events that include electrical discharges, loud thunder, & usually large amounts of rain, hail, and even snow. About 40,000 thunderstorms occur every day in the world. Thunderstorms are most frequent in the Earth's equatorial regions, and are most powerful in the United States, particularly in the Midwest and South.

Inside the Vortex

Earth's weather is capable of producing a variety of whirling (or tornadic) winds. These include dust devils, waterspouts and tornadoes. Although they share the common element of a rotating column of air, they are actually formed in different ways. Dust devils and small whirlwinds are created by intense local heating of the ground that causes the air to rise rapidly.

Tropical Storms

The Earth's atmosphere is a complex system that seeks equilibrium. The Earth's orbit roughly the sun & the tilt of its axis means that the tropical latitudes build up a great deal of heat. Tropical storms are the way that this heat is dissipated to the middle latitudes.

Becoming an Amateur Weather Watcher

Our atmosphere produces a fascinating array of weather events. In many areas of the world, weather is changing constantly and challenging us as we live, work and play. Recent times have seen the introduction of professional quality instruments for use by amateurs and enthusiasts.

Water Vapor Essential to Weather

Water vapor exists as an invisible gas throughout our atmosphere. About 90 percent of this water vapor is added to Earth's atmosphere through evaporation from the oceans. When the sun heats the water in the oceans, some water changes from a liquid to a gas and rises in the warm air.