Tutorial Update: Hazard Class

[l-pierini]

This PR updates the climada_hazard_Hazard.ipynb Hazard Class tutorial.

Changes proposed in this PR:

• Rephrased introduction text for improved clarity
• Small code addition to automatically create the output folder if it does not exist

Notes:

• The tutorial run smoothly, so figures and outputs remain unchanged

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• Documentation updated
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[chahank]

Suggested change

	"A hazard describes weather events such as storms, floods, droughts, or heat waves, both in terms of probability of occurrence as well as physical intensity.\n",
	"A hazard describes climate and weather extremes such as storms, floods, droughts, or heat waves, in terms of events which have a physical intensity and a probability (in the frequentist sense) of occurence. Each hazard event is described as one geographical map of intensity in a given unit (e.g., flood depth in meters, wind speed in m/s, heat waves in number of days, ...) \n",

[chahank]

Maybe here one can add a few sentences on the fact that hazard can represent probabilistic event sets, single events, story lines, climate model time series, etc...

[chahank]

Maybe something like this? (links need to inserted)

Suggested change

	"Each hazard class collects observational data or model simulations and transforms them, if necessary, in order to construct a coherent event database. \n",
	"Stochastic realizations can be generated by accounting for the frequency and key intensity characteristics (such as local water depth for floods or gust speed for storms) of the input events, producing a probabilistic ensemble for each.\n",
	"CLIMADA provides therefore an event-based probabilistic approach which does not assume a-priori probability distributions. Note that one can also reduce the probabilistic approach to a deterministic approach (e.g., story-line or forecasting) by defining the frequency to be 1.\n",
	"For certain hazards, there exists dedicated subclasses, such as `TropicalCyclones`, `Wildfires`, or `RiverFlood` which collect observational data or model simulations and transforms them, if necessary, into a CLIMADA `Hazard` object. Most of these data models are found in the climada petals repository. Note that these classes are built for specific purposes and are not general data models. \n",
	"CLIMADA provides therefore an event-based probabilistic approach which does not assume a-priori probability distributions. Note that one can also reduce the probabilistic approach to a deterministic approach (e.g., story-line or forecasting) by defining the frequency to be 1.\n",

I do not understand what the two last sentences are supposed to mean.

[chahank]

I think I would remove that. The CLIMADA hazard data classes are relatively limited in scope, so I would not put them forth so much. Rather, explain that one should use relevant external hazard data sources when possible.

[chahank]

I think this is a very useful update. I added a few suggestions for some sentences that I would interpret differently.