convertPrecipitationToInch (value, valueUnit) {
		if (valueUnit && valueUnit.toLowerCase() === "cm") return value * 0.3937007874;
		else return value * 0.03937007874;
	}
Convert precipitation value into inch
@param {number} value the precipitation value for convert
@param {string} valueUnit can be 'mm' or 'cm'
@returns {number} the converted precipitation value