Enter the 500 millibar environmental temperature and the 500 millibar parcel temperature into the Calculator. The calculator will evaluate the Showalter Index.

## Showalter Index Formula

SI = T500 - Tp500

Variables:

- SI is the Showalter Index ()
- T500 is the 500 millibar environmental temperature
- Tp500 is the 500 millibar parcel temperature

To calculate Showalter Index, subtract the 500 millibar parcel temperature from the environmental temperature at the same pressure.

## How to Calculate Showalter Index?

The following steps outline how to calculate the Showalter Index.

- First, determine the 500 millibar environmental temperature.
- Next, determine the 500 millibar parcel temperature.
- Next, gather the formula from above = SI = T500 – Tp500.
- Finally, calculate the Showalter Index.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

500 millibar environmental temperature = 4

500 millibar parcel temperature = 5