Marine Cloud Brightening (MCB) is a proposed solar radiation management technique that may be able to reduce water temperature on the Great Barrier Reef during marine heatwave conditions. MCB requires increasing the available cloud condensation nuclei (CCN) available to low level marine clouds as they form. Additional cloud condensation nuclei increase the number of droplets within the cloud, whilst maintaining the quantity of liquid water, other parameters being equal, this leads to higher cloud reflectivity or albedo. An environmentally benign method of generating the enormous quantities of additional nuclei required is to atomise sea water. Generating the required quantities and size distribution of the sea spray is a considerable engineering challenge that has not previously been solved. Here we describe the in-laboratory development of a suitable nozzle and its subsequent upscaling to produce sufficient correctly sized droplets to enable the world’s first in-situ field trials of MCB. The current prototype produces 1014 droplets per second from 45mL of water per second, with approximately 50 % within an acceptable range for cloud brightening. The current prototype is now of sufficient scale to facilitate cloud perturbation studies which we anticipate will enable a rapid advance in our understanding of aerosol – cloud microphysical interactions.