# Vapour-Pressure Deficit Virtual Sensor

**Vapor-pressure deficit (VPD)** is one of the methods growers use to measure humidity in a greenhouse or growing environment. It allows growers to gauge the impact of humidity on plant growth and development.

VPD in Aranet Cloud is calculated according to the formula:

<div data-with-frame="true"><figure><img src="https://forum.aranet.com/site/assets/files/4310/ac_vpd_formula.png" alt=""><figcaption></figcaption></figure></div>

Required measurements:

<div data-with-frame="true"><img src="https://forum.aranet.com/site/assets/files/4310/ac_vpd_formula01.png" alt="" width="162"></div>

The default metric of VPD is *kPa.*

To create a virtual VPD sensor, navigate to the **SENSORS** menu -> **VIRTUAL SENSOR**S tab and press the **NEW VIRTUAL SENSOR** button:

<div data-with-frame="true"><figure><img src="/files/38vTfwfvNQQPLDT0rQCZ" alt=""><figcaption></figcaption></figure></div>

Select Vapour-pressure deficit sensor:

<div data-with-frame="true"><figure><img src="/files/QAYC2OkLkhUVlPCize1f" alt=""><figcaption></figcaption></figure></div>

Give the sensor a name, select the source sensors, and press the **CREATE** button:

<div data-with-frame="true"><figure><img src="/files/VEfcUAqAQy5jnEt1mb7F" alt=""><figcaption></figcaption></figure></div>

Sensor is created:

<div data-with-frame="true"><figure><img src="/files/j3RkoXCIuakmZP27unGL" alt=""><figcaption></figcaption></figure></div>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://help.aranet.com/aranet-cloud-page/aranet-cloud-landing-page/user-interface-and-core-features/sensors/virtual-sensors/vapour-pressure-deficit-virtual-sensor.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.