This sensor is used to measure plant leaf temperature through the infrared radiation emitted from the tip of the adjustable arm. By using this data combined with that of the temperature and relative humidity sensor, you can obtain the vapor pressure deficit (VPD). Since it can have a significant impact on plant growth and health, this data is crucial. Plants transpire water to cool themselves and VPD influences the amount of water that plants can lose.

When VPD is high, it means that air is dry and plants need to transpire more water to cool down. This can lead to water stress, which can damage plants and reduce crop yields.

A low VPD indicates that air is humid and plants do not need to transpire much water to cool down. This can lead to fungal diseases, which can spread more easily in high humidity conditions.

By knowing the VPD of a plant, farmers can take measures to ensure that plants receive the right amount of water and are protected from diseases.