If there is wifi availability over the area you can use some esp8266 module (Nodemcu) else you can add a gsm module to your Arduino (probably some sim800 or similar modules). Once you have decided your hardware you can use some cloud service like thingspeak or some similar iot cloud service to upload your data to cloud. Note thingspeak free version offers uploading or downloading data every with a minimum if 15 sec. On the client / receiving end you can use the same hardware and download data from the sensor nodes. You can use protocols like MQTT or HTTP requests to transmit and receive data.