Climate and the Biosphere: Unit Overview

Why study weather, climate, and the biosphere?

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Afternoon sky with fair-weather clouds. Photo courtesy of: Our Changing Planet.

Weather and climate are all around us. Take a moment to look at the sky; maybe you see clouds, fog, or rain. Feel the wind; smell the familiar aromas around you. The sky, or atmosphere, connects the land, ocean, and life. It is something that everyone on Earth shares. It protects us and gives us life, and yet it is easy to take for granted. Think for a moment about how the weather has affected your life this week: was it cold? hot? did it rain or snow? or was it dry and windy? Maybe you experienced all of these weather patterns. Now think about what you might call normal weather for your area, also known as climate. Was the weather typical for this time of year? For example, if you are reading this in the fall, are nighttime temperatures beginning to cool?

Short-term variations in atmospheric phenomena that interact with the environment, and affect life, are called weather. These variations take place on a timescale of minutes, hours, days, weeks, or occasionally months. Weather is defined as the state of the atmosphere at a given location and time. It includes such variables as temperature, precipitation, cloudiness, wind speed and direction, and relative humidity. The study of atmospheric phenomenon is known as meterology. The word meterology comes from the Greek word meteorous, meaning high in the air. By this definition a cloud, raindrop, fog, dust particle, lightning, or wind are all types of meteors. Meteorologists study these phenomena.

Climate, on the other hand, is a long-term pattern. By one definition, it is the statistical average of the weather conditions for a particular area over a long term, usually a 30-year period. Climate patterns allow us to have a general sense of the weather to expect at any given time. Because it is defined by long-term averages, it is more consistent and predictable than weather; just think of how we associate seasons and events with typical weather patterns. For example, in the northern United States we can assume it will snow in the winter and rain in the spring. In places like Arizona and New Mexico, there are summer rains that come during what is known as the "monsoon season." Farmers depend upon these patterns to know when to plant; insurance agencies use them to know which areas are prone to extreme weather; and energy managers use climate data to predict when energy demands for heating and cooling should peak. Climatologists study long-term patterns in weather and climate in order to make these types of predictions. These scientists also work to further understand how humans affect climate.

What will I learn?

In this unit on climate, weather, and the biosphere, you will have articles to read, hands-on investigations or labs, videos, computer animations, maps, graphics, and class discussions. The combination of these experiences will help you understand the ways in which energy from the sun interacts with Earth's atmosphere, land, oceans, and biosphere (all living things) to give us weather and climate. Another key idea of this unit is to introduce the very different timescales at which weather and climate operate. For example, fast-moving summer storms may last for a few minutes while winter lasts for several months. And normal, periodic changes in Earth's orbit can cause climate changes ("interglacial periods," for example) that last for tens of thousands of years.

As you work through the lessons, you will learn more about weather and climate patterns, their causes and the impacts that they have on life on Earth. You will get a sense of how the Earth's systems, such as wind and ocean currents, distribute incoming solar energy around the planet, making Earth habitable for a broad range of life. You will develop a sense of the factors that control climate and how climate and weather affect all of our lives, including the lives of plants and trees. You will learn more about climate science and how weather and climate are related, and yet different. After completing this unit, you will have a better understanding of what you hear on the news, and you will understand what scientific reports are telling us about climate change and global warming.