The Role of Water in Changing the Earth
As we continue to explore how Earth changes as a result of both natural and anthropogenic processes and impacts, we introduce one of the primary agents on the surface of the Earth: water.
Water is one of the most abundant molecules on Earth above the crust. In three different phases, it comprises the oceans, the ice sheets, terrestrial surface water and groundwater, and a small, but important, percentage of the atmosphere. Unlike many other major molecules found on Earth, which are predominantly stable at the surface, water constantly and readily transforms between liquid, solid, and gas phases through the exchange of heat energy. The transformation and transport of water molecules between the oceans, the atmosphere, and land is called the hydrologic cycle.
The ability of water to so readily transform, transport, and hold and exchange heat energy also makes it incredibly powerful as an agent of change. From local scales to global, water sculpts and shapes the Earth surface and impacts human civilizations through day-to-day precipitation, severe weather such as tornadoes and hurricanes, wave action and tsunamis, ice build-up and movement, floods, droughts, and the slow and steady erosion performed by creeks, streams, and rivers in their rush to get back to the ocean. That humans have spent centuries trying to harness and control the power of all this water is no surprise, and makes us accomplices in the change that is wrought both slowly and rapidly across the face of the Earth.
Let's start by getting a better idea of where water is on Earth and in what phase (liquid, gas, or solid) it exists. Log into BBLearn and under Module 4, complete "Assignment 4.1: The Hydrologic Cycle."
Water is one of the most abundant molecules on Earth above the crust. In three different phases, it comprises the oceans, the ice sheets, terrestrial surface water and groundwater, and a small, but important, percentage of the atmosphere. Unlike many other major molecules found on Earth, which are predominantly stable at the surface, water constantly and readily transforms between liquid, solid, and gas phases through the exchange of heat energy. The transformation and transport of water molecules between the oceans, the atmosphere, and land is called the hydrologic cycle.
The ability of water to so readily transform, transport, and hold and exchange heat energy also makes it incredibly powerful as an agent of change. From local scales to global, water sculpts and shapes the Earth surface and impacts human civilizations through day-to-day precipitation, severe weather such as tornadoes and hurricanes, wave action and tsunamis, ice build-up and movement, floods, droughts, and the slow and steady erosion performed by creeks, streams, and rivers in their rush to get back to the ocean. That humans have spent centuries trying to harness and control the power of all this water is no surprise, and makes us accomplices in the change that is wrought both slowly and rapidly across the face of the Earth.
Let's start by getting a better idea of where water is on Earth and in what phase (liquid, gas, or solid) it exists. Log into BBLearn and under Module 4, complete "Assignment 4.1: The Hydrologic Cycle."