Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit the NASA Salinity website for more information.

Education: Activities & Documents

Heat Flow and Latent Heat
Lab setup
Activity 4.5: Heat Flow and Latent Heat (pp. 37-38; click here for videos accompanying this activity). A good grasp of the underlying principles of thermal physics is essential for understanding how the ocean functions and how it impacts climate. Thermal physics is one of the science subjects that students are familiar with and experience on a daily basis, but intertwined with the experiential knowledge they bring to class comes a mixed bag of misconceptions that must be identified and addressed. Example misconceptions include an inability to differentiate between heat and temperature, the notion that transfer of heat will always result in a temperature rise, and a misunderstanding of latent heat. The purpose of this activity is to review basic concepts of thermal physics and highlight applications to ocean processes by focusing on the concept of latent heat.

When an object gains heat, two things can happen: the temperature of the object can rise, or the object can change its state without a measurable change in temperature (e.g., ice melting into water). Most materials have two state transitions: from solid to liquid and from liquid to gas. The heat needed to change the state of a material is called latent heat of fusion (for changing from solid to liquid) and latent heat of vaporization (for changing from liquid to gas). Latent heats of fusion and vaporization for water are high and have many important consequences for Earth's climate. Credit: Karp-Boss, L., E. Boss, H. Weller, J. Loftin, and J. Albright (2009). Teaching Physical Concepts in Oceanography: An Inquiry Based Approach. Oceanography 22(3), supplement, 48 pp.