🔍 Key Concepts
• Use the psychrometric chart: dry bulb along the bottom (horizontal axis) and wet bulb along the left side (slanted lines).
• Understand that relative humidity lines are the smooth, curved lines labeled 10%, 20%, 30%, etc., running up through the chart.
• The point where the 76°F dry bulb line and the 58°F wet bulb line cross will fall on or between these % curves.
💭 Think About
• First, locate 76°F on the bottom axis and draw a line straight up from it. Which part of the chart does this vertical line pass through?
• Next, locate 58°F on the wet‑bulb scale and follow that slanted line until it meets your 76°F vertical. Which labeled humidity curve is that intersection closest to?
• Compare the relative humidity value at that curve with the answer choices; if it falls between two curves, which option is the closest match?
✅ Before You Answer
• Be sure you are reading dry bulb from the bottom horizontal scale, not from the right side (that is dew point).
• Confirm you have the correct wet bulb line—these are slanted, nearly straight lines running up and to the right from the left scale.
• Verify which relative humidity curve (10%, 20%, 30%, etc.) passes exactly through, or closest to, the intersection point before choosing an answer.