Is there any database or API that can provide data present in Atlas books for example, list of countries, population, temperature etc.
For the climate data, there is PlanetOS API with a number of public datasets that have modelled and reanalysis data. You can access that data per geo point (LonLat) and time range in JSON or CSV format. Or you can acquire raster data via OpenDAP API.
Disclaimer: I work for PlanetOS, we support & promote public and open source projects.
So here are some examples of datasets and details about the API:
- Global forecasts dataset (temperature, humidity, etc)
- Re-analysis (from satellite data) of global ocean temperature
I suggest to look into CartoDB for the civic data, they have a bunch of civic data sources integrated.