🔍 Key Concepts

• Psychrometric chart usage – how to move from a known dry-bulb temperature and relative humidity to find the dew point. • Difference between dry-bulb temperature, wet-bulb temperature, and dew point temperature on the chart. • How constant humidity ratio / grains of moisture lines relate to dew point temperature at another location on the chart.

💭 Think About

• On the chart, start at 80°F on the dry-bulb (horizontal) axis and move up until you intersect the 70% relative humidity curve. From that point, which direction do you move to read the dew point temperature? • Notice that the lower-left slanted scale is labeled "Wet Bulb and Dew Point Temperature". How do the slanted lines that pass through your state point relate to that scale? • If you follow the correct slanted line from your 80°F/70% RH point down to the wet‑bulb/dew‑point scale, which of the answer choices most closely matches that temperature reading?

✅ Before You Answer

• Be sure you are using the 70% RH curve, not 60% or 80%. • Confirm you are reading from the wet-bulb and dew point temperature scale along the left edge, not the dry-bulb scale along the bottom. • Double‑check that you are following the correct slanted line from the 80°F/70% RH intersection all the way to the labeled dew‑point scale before choosing among 64°F, 67°F, 70°F, or 73°F.