Salinity and Density

Front

Density Noun

---

[den-si-tee]

Back

Density

---

The measure of a substance's mass per unit of its volume, a fundamental physical property of matter.

---

Example: This image shows that for two objects of the same size (volume), the one with more matter (mass) packed inside is heavier and has higher density.

Front

Mass Noun

---

[mas]

Back

Mass

---

A measure of the amount of matter contained within a physical body, independent of its size or volume.

---

Example: This image uses a balance scale to show that the apple has more mass than the 1-gram weight, causing the scale to tip.

Front

Volume Noun

---

[vol-yoom]

Back

Volume

---

The amount of three-dimensional space that a substance or object occupies or that is enclosed within a container.

---

Example: This image shows how to measure the volume of a liquid in a graduated cylinder by reading the scale at the bottom of the meniscus.

Front

Relative Density Noun

---

[rel-uh-tiv den-si-tee]

Back

Relative Density

---

The ratio of the density of a substance to the density of a given reference material, such as water.

---

Example: This image shows that an object's density relative to water determines if it floats or sinks. The pumice stone is less dense than water and floats.

Front

Salinity Noun

---

[suh-lin-i-tee]

Back

Salinity

---

The measure of the total amount of all dissolved solids, primarily salts, present in a body of water.

---

Example: This diagram shows that seawater's salinity comes from dissolved salts. The salts, mostly chloride and sodium, make up a small percentage of the total.

Front

Evaporation Noun

---

[ih-vap-uh-rey-shuhn]

Back

Evaporation

---

The process where a liquid transitions into a gas, which increases water salinity by removing fresh water molecules.

---

Example: Heat energy from the sun causes water to change from a liquid to a gas (water vapor), a process called evaporation.

Front

Precipitation Noun

---

[pri-sip-i-tey-shuhn]

Back

Precipitation

---

Water released from clouds as rain or snow, which adds fresh water to the ocean and decreases its salinity.

---

Example: This diagram shows precipitation as part of the larger water cycle, where water falls from clouds as rain or snow onto the land and water.

Front

Hydrothermal Vent Noun

---

[hahy-droh-thur-muhl vent]

Back

Hydrothermal Vent

---

A fissure on the seafloor from which geothermally heated water, rich in dissolved minerals, discharges into the ocean.

---

Example: Cold, dense seawater sinks into the ocean floor, is heated by magma, and rises as hot, less-dense water through a vent, carrying minerals.

Front

Dissolved Solids Noun

---

[dih-zolvd sol-ids]

Back

Dissolved Solids

---

Any minerals, salts, metals, or other non-volatile substances that are dissolved in a liquid, such as water.

---

Example: This diagram shows solute particles (the dissolved solids) evenly mixed within a solvent to form a solution, which is the basis for understanding salinity.

Front

Mixed Layer Noun

---

[mikst ley-er]

Back

Mixed Layer

---

The upper layer of the ocean, actively mixed by wind and waves, resulting in relatively uniform temperature and salinity.

---

Example: This diagram shows the ocean's 'mixed layer' near the surface, where properties like salinity are uniform due to mixing by wind and waves.