In environmental science, air contains water in a gaseous form that is known as what?

Introduction / Context:
The water cycle and the presence of water in different states are fundamental concepts in environmental science and geography. In the atmosphere, water can exist as solid ice crystals, liquid droplets, or water in the gaseous state. Understanding the correct term for water in the gaseous state in air is important for topics such as humidity, cloud formation, and weather patterns. This question asks for the term used to describe water in its invisible gaseous form in the air.

Given Data / Assumptions:

• The focus is on water in a gaseous form present in air.
• The options given are vapour, droplets, humidity, and none of the above.
• We assume basic school level definitions for states of matter and atmospheric terms.

Concept / Approach:
Water can exist in three main physical states: solid (ice), liquid (water), and gas (water vapour). In the atmosphere, water in the gaseous state is called water vapour and is invisible to the naked eye. When water vapour cools and condenses, it forms tiny liquid droplets that make up clouds and fog. The term humidity refers to the amount of water vapour present in the air, not the gaseous form itself. Therefore, the correct scientific term for water in its gaseous state in the air is vapour or specifically water vapour.

Step-by-Step Solution:
1. Identify that the question is about the state of water in the air, specifically the gaseous form.2. Recall that when water evaporates, it turns into water vapour, which mixes with the air.3. Recognize that “vapour” refers to the gaseous state of a substance that is usually liquid or solid at room temperature.4. Compare the options: “Droplets” refers to tiny liquid particles, not gas. “Humidity” refers to the amount of water vapour in the air but not the form itself.5. Since the question asks for the form of water, the correct term is “Vapour.”

Verification / Alternative check:
School science diagrams of the water cycle show evaporation from oceans, lakes, and plants, forming water vapour that rises into the atmosphere. Later, this vapour cools and condenses into tiny water droplets forming clouds. Meteorological reports that discuss humidity and dew point are referring to the concentration of water vapour in the air. This text and these diagrams consistently use the term “water vapour” for the gaseous state, confirming that “vapour” is the proper answer for the form of water in air.

Why Other Options Are Wrong:
Option B, “Droplets,” is incorrect because droplets are tiny particles of liquid water that appear when vapour condenses, such as in clouds and fog; they are not the gaseous form. Option C, “Humidity,” is wrong because it refers to how much water vapour is present in the air, not to the physical form of water. Option D, “None of the above,” is incorrect because one of the provided options, vapour, is accurate. Thus, only “Vapour” correctly describes water in its gaseous form in the atmosphere.

Common Pitfalls:
Students sometimes confuse humidity with vapour, thinking that humidity is another word for the gaseous form of water. In reality, humidity is a measure or description of the amount of water vapour present, not the state itself. Another pitfall is to imagine that water in the air must always be visible as droplets or mist, whereas water vapour is actually invisible under normal conditions. Remember that vapour is the gaseous state, droplets are liquid, and humidity describes how much vapour is present.

Final Answer:
Air contains water in a gaseous form called vapour, more specifically water vapour.