Final answer:
A moist layer on a skew T plot is usually found near the Earth's surface, within the first few kilometers of the troposphere.
Step-by-step explanation:
On a skew T plot, a moist layer is usually indicated by a region with a negative lapse rate, which means that temperature decreases with increasing altitude. This moist layer is typically found in the lower levels of the atmosphere, near the Earth's surface. The exact height of the moist layer can vary depending on various factors such as weather conditions and location, but it is often found within the first few kilometers of the troposphere.