🔍 Key Concepts
• Use the psychrometric (relative humidity) chart: dry bulb values are along the bottom, wet bulb values are along the slanted/curved scale.
• Remember that relative humidity lines are usually slanted, labeled in percent (e.g., 40%, 50%, 60%).
• Pay attention to the difference between dry bulb and wet bulb temperatures (wet‑bulb depression) and how that shifts you along the chart.
💭 Think About
• First, locate 80°F on the dry bulb (bottom) axis. From that point, what line do you follow upward or upward-right to enter the chart?
• Next, find 70°F on the wet bulb scale. Where does the line through this wet bulb temperature intersect the vertical (or near-vertical) line for 80°F dry bulb?
• At that intersection point, which labeled relative humidity curve passes closest through it?
✅ Before You Answer
• Confirm you are reading dry bulb from the horizontal bottom axis and wet bulb from the appropriate slanted/side scale, not mixing them up.
• Make sure you are following the correct relative humidity curves (they are typically marked 10%, 20%, 30%, etc.).
• Verify that the intersection point lies between the correct humidity curves and choose the closest labeled percentage that matches the multiple‑choice options.