Question

what is relative humidity?
10°c
20°c
30°c
capacity
capacity
water
vapor
water
vapor
water
vapor
100% rh
50% rh
30% rh
what is relative humidity?
the amount of water vapor in the air per unit of air
the temperature at which water vapor condenses
the ratio of current temperature to maximum possible temperature
the ratio of air pressure at sea level to air pressure at a given altitude

Explanation:

To determine the correct definition of relative humidity, we analyze each option:

• Option 1: Relative humidity is related to the amount of water vapor relative to the maximum capacity at a temperature, not just per unit air (that's absolute humidity - like the blue part in the droplets). But the first option's wording is close as relative humidity involves water vapor in air. Wait, no—wait, let's re - check. Wait, the first option says "The amount of water vapor in the air per unit of air"—no, that's absolute humidity. Wait, no, maybe I messed up. Wait, the diagram shows different temperatures (10°C, 20°C, 30°C) with water (blue) and capacity (orange). At 10°C, 100% RH (water = capacity), 20°C 50% (water is half of capacity), 30°C 30% (water is 30% of capacity). So relative humidity is the ratio of actual water vapor (water) to the maximum capacity (capacity) at a given temperature. But the options: Let's re - evaluate each option:
• Option 1: "The amount of water vapor in the air per unit of air"—this is absolute humidity (mass of water vapor per volume of air), not relative. But maybe the option is phrased simply. Wait, no, the other options are wrong:
• Option 2: "The temperature at which water vapor condenses"—that's dew point, not relative humidity.
• Option 3: "The ratio of current temperature to maximum possible temperature"—this has nothing to do with humidity, it's about temperature ratio, not water vapor.
• Option 4: "The ratio of air pressure at sea level to air pressure at a given altitude"—this is about pressure altitude relationship, not humidity.

Wait, maybe I mis - analyzed option 1. Wait, relative humidity is the ratio of the actual water vapor content to the maximum possible water vapor content (capacity) at a given temperature. But the first option says "the amount of water vapor in the air per unit of air"—maybe in simple terms, relative humidity is about how much water vapor is in the air compared to how much it can hold. But the other options are clearly wrong. So the first option is the best among the given ones, as the others are unrelated (option 2 is dew point, option 3 is temperature ratio, option 4 is pressure ratio).

Answer:

The amount of water vapor in the air per unit of air