Ari's Planet

To plan my itinerary, I sort of decided on regions of the world and countries that would be interesting to visit. Then, I planned the route both geographically and based on the climate, with the intent of minimizing weather extremes (cold, heat, humidity, rain), minimizing flights, and maximizing interesting places. Geography is ascertained with a map. Climate took more work.

Guidebooks provide some climate information, but I wanted a more automatic and general solution. The food and agriculture organization of the United Nations provides the Local Monthly Climate Estimator (LocClim) service. This service takes the coordinates of a location (latitude, longitude, altitude) and computes approximate climate (temperature, rainfall, vapor pressure) by interpolating from neighboring weather stations. I used the locations of capital cities, since these were easy to find online. Regional cities could also be used where significant variation is expected (e.g., India, China).

The comfort of a climate can be succinctly described with a heat index (HI), which describes the apparent temperature, taking into consideration the relative humidity. The heat index is proportional to humidity and can be computed from the relative humidity and temperature. The LocClim service provides temperature and vapor pressure data, so the first task is converting vapor pressure to relative humidity, which is just the vapor pressure divided by the saturation vapor pressure at a given temperature. There are various equations for computing the saturation vapor pressure, I used one of the simplest six order polynomial (Flatau et. al.,1992). The heat index uses an equation from Steadman, R.G., 1979. Next, I arbitrarily defined cutoff points for comfortable weather at a given heat index. I considered a HI of <5C or >=31C to be uncomfortable.

I used a spreadsheet where I could enter different country names with a trip start date and duration for each country. The year was divided into weeks with a visual indication of whether I would be in the country, using color to indicate the best times to visit (based on climate), and whether I was in each country during these times. This made it easy to play around with the order of visitation and length of stay in each country.

This approach provided the general outline for my trip. All the dates are flexible. I will only be booking the first three flight segments (NY->SF->Tokyo->Ulaanbattaar). I can skip countries, stay longer in others (subject to visa requirements), etc. I am not wedded to this itinerary, rather, it serves as a general guide. I am currently researching more specific interests and sites within each country, using the usual sources: guidebooks, other books, the Internet. I would like to provide a nice Google Earth route, but Google Earth's route tracing tools are not very convenient to use.