I'm currently reading a university textbook on processes that result in rainfall events. In the current processes, I'm reading there is a cold front that basically pushes warm air upwards which results in pretty heavy rain. A little before that, the process that a warm front basically moves above cold air which results in winter rain with a long duration. In the textbook I find the following sentences:
Typically, cold fronts have relatively steep slopes, about 1 in 30 to 40, while warm fronts have slopes of 1 in 60 to 120; thus precipitation is usually more intense and areally more concentrated at cold fronts than at warm fronts.
What means "1 in 30"? Could it be 1/30 = 0.0333 = 3.3% ? 1 in 60 = 1/60 = 0.016666 = 1.7%.
That would result in a steeper slope for cold fronts. Is my understanding correct? Is a 2-3% slope for warm air pushed by cold fronts realistic?